ORCID Profile
0000-0003-3468-4773
Current Organisation
Macquarie University
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In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Photodetectors, Optical Sensors and Solar Cells | Electrical and Electronic Engineering | Nanofabrication, Growth and Self Assembly | Quantum Physics | Colloid and Surface Chemistry | Nanomaterials | Nanotechnology | Photovoltaic devices (solar cells) | Nanomanufacturing | Nanomaterials | Functional Materials | Nanotechnology | Materials Engineering | Microtechnology | Photonic and electro-optical devices sensors and systems (excl. communications) | Composite and Hybrid Materials | Quantum Information, Computation and Communication | Condensed Matter Imaging
Expanding Knowledge in Technology | Expanding Knowledge in the Physical Sciences | Solar-Photovoltaic Energy | Expanding Knowledge in Engineering | Expanding Knowledge in the Chemical Sciences |
Publisher: IOP Publishing
Date: 12-1999
Abstract: The fabrication of a self-organized two-dimensional array of gold nanodots encapsulated by alkanethiol on a silicon substrate is presented. An experimental study on the mechanical stability of such a quantum dot structure was carried out. The results of this work demonstrate that gold nanodots encapsulated by alkanethiol can maintain their position strongly on a silicon substrate rather than be destroyed in a destructive environment. Therefore it is believed that such a nanostructure is useful for the development of future nanoelectronics.
Publisher: Wiley
Date: 31-03-2017
Publisher: IOP Publishing
Date: 09-2016
Publisher: IEEE
Date: 06-2013
Publisher: OSA
Date: 2013
Publisher: Inderscience Publishers
Date: 2011
Publisher: IOP Publishing
Date: 17-12-2012
DOI: 10.1088/0022-3727/46/2/024003
Abstract: Silicon quantum dot (QD)-based ‘all-silicon’ tandem solar cells have emerged as a promising third generation photovoltaic approach to realize high-efficiency and cost effective solar cells. This approach exploits the quantum confinement effect of silicon QDs embedded in a dielectric matrix to engineer the effective electronic bandgap of a solar cell material. Research work in our group has shown that such a Si QD solar cell can be fabricated by co-sputtering of thin layers of Si-rich dielectric sandwiched between stoichiometric dielectric layers which crystallize to form Si QDs of uniform size on annealing. The Si-richness in the Si-rich layer plays an important role in formation of uniform size and shape. The matrix and barrier layer materials also affect the formation of Si QDs. The bandgap tunability of such Si QD superlattice structures has been clearly demonstrated by photoluminescence and electroluminescence measurements. Doping of Si QD layers has been achieved by impurity incorporation of P, Sb or B in the Si-rich layers. Strong evidence of effective doping has been demonstrated from the enhanced conductivity, from the dopant concentrations extracted from MOS structures and from the formation of rectifying p–n junctions which give an open circuit voltage ( V oc ) of 492 mV. The doping mechanism is more likely to be modified interface doping rather than direct doping to the Si QDs.
Publisher: Wiley
Date: 16-10-2017
Publisher: IOP Publishing
Date: 23-09-2011
Publisher: Wiley
Date: 02-2019
Abstract: This paper provides deep understanding of the formation mechanism of perovskite film fabricated by sequential solution-based methods. It compares two sequential spin-coating methods for Cs
Publisher: American Chemical Society (ACS)
Date: 22-06-2015
DOI: 10.1021/ACS.NANOLETT.5B01405
Abstract: Organic-inorganic halide perovskite has emerged as a very promising material for solar cells due to its excellent photovoltaic enabling properties resulting in rapid increase in device efficiency over the last 3 years. Extensive knowledge and in-depth physical understanding in the excited state carrier dynamics are urgently required. Here we investigate the fluorescence intermittency (also known as blinking) in vapor-assisted fabricated CH3NH3PbBr3 perovskite. The evident fluorescence blinking is observed in a dense CH3NH3PbBr3 perovskite film that is composed of nanoparticles in close contact with each other. In the case of an isolated nanoparticle no fluorescence blinking is observed. The "ON" probability of fluorescence is dependent on the excitation intensity and exhibits a similar power rule to semiconductor quantum dots at higher excitation intensity. As the vapor-assisted fabricated CH3NH3PbBr3 perovskite film is a cluster of nanoparticles forming a dense film, it facilitates mobile charge migration between the nanoparticles and charge accumulation at the surface or at the boundary of the nanoparticles. This leads to enhanced Auger-like nonradiative recombination contributing to the fluorescence intermittency observed. This finding provides unique insight into the charge accumulation and migration and thus is of crucial importance for device design and improvement.
Publisher: Elsevier BV
Date: 08-2008
Publisher: Elsevier BV
Date: 03-2015
Publisher: American Chemical Society (ACS)
Date: 27-10-2022
Publisher: American Chemical Society (ACS)
Date: 15-02-2021
Publisher: American Chemical Society (ACS)
Date: 18-12-2014
DOI: 10.1021/JP511054G
Publisher: IEEE
Date: 06-2013
Publisher: Elsevier BV
Date: 08-2017
Publisher: IOP Publishing
Date: 24-12-2019
Abstract: The unique tunable bandgaps and straightforward synthesis of colloidal quantum dots make them promising low-cost materials for photovoltaics. High-performance colloidal quantum dot solar cells rely on good-quality electron transporting layers (ETLs) to make carrier selective contacts. Despite extensive use of n-type oxides as ETLs, a detailed understanding of their surface and interface states as well as mechanisms to improve their optical properties are still under development. Here, we report a simple procedure to produce MgCl
Publisher: AIP Publishing
Date: 28-03-2016
DOI: 10.1063/1.4945594
Abstract: We have investigated the ultrafast carrier dynamics in a 1 μm bulk In0.265Ga0.735N thin film grown using energetic neutral atom-beam lithography/epitaxy molecular beam epitaxy. Cathodoluminescence and X-ray diffraction experiments are used to observe the existence of indium-rich domains in the s le. These domains give rise to a second carrier population and bi-exponential carrier cooling is observed with characteristic lifetimes of 1.6 and 14 ps at a carrier density of 1.3 × 1016 cm−3. A combination of band-filling, screening, and hot-phonon effects gives rise to a two-fold enhanced mono-exponential cooling rate of 28 ps at a carrier density of 8.4 × 1018 cm−3. This is the longest carrier thermalization time observed in bulk InGaN alloys to date.
Publisher: American Vacuum Society
Date: 07-2007
DOI: 10.1116/1.2756556
Abstract: Si-rich amorphous silicon carbide thin films were prepared by magnetron cosputtering and were subsequently annealed to form Si nanocrystals embedded in a SiC matrix. A sputter target consisted of a patterned Si wafer on top of a carbon target. The ratio of carbon to silicon in deposited films was adjusted by means of a different silicon wafer open area. X-ray photoelectron spectroscopy spectra show that various compositions were obtained by changing the sputtered area ratio of carbon to silicon target. Analysis of atomic force microscopy shows that surface roughness increases significantly after annealing. Transmission electron microscopy reveals that Si nanocrystals do not form at temperatures less than 800°C, while they are clearly established, with sizes ranging from 3to7nm, as the temperature is at 1100°C. IR spectra show that increase in annealing temperature for the Si-rich Si1−xCx (x& .5) films favors the formation of Si–C bonds and increase of the short-range order. Optical studies show a blueshift of the optical absorption edge in transmission spectra and increase in the optical band gap with increasing annealing temperature. Optical band gaps upon annealing were correlated with increasing Si–C bond density and ordering in the SiC matrix due to structural relaxation of the films.
Publisher: Springer Science and Business Media LLC
Date: 10-02-2011
Abstract: In this paper, a positive effect of rapid thermal annealing (RTA) technique has been researched and compared with conventional furnace annealing for Si nanocrystalline in silicon carbide (SiC) matrix system. Amorphous Si-rich SiC layer has been deposited by co-sputtering in different Si concentrations (50 to approximately 80 v%). Si nanocrystals (Si-NC) containing different grain sizes have been fabricated within the SiC matrix under two different annealing conditions: furnace annealing and RTA both at 1,100°C. HRTEM image clearly reveals both Si and SiC-NC formed in the films. Much better "degree of crystallization" of Si-NC can be achieved in RTA than furnace annealing from the research of GIXRD and Raman analysis, especially in high-Si-concentration situation. Differences from the two annealing procedures and the crystallization mechanism have been discussed based on the experimental results.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6TC01276K
Abstract: A detailed optical analysis of the absorption distribution, parasitic absorption and reflection losses in various semi-transparent perovskite solar cell structures and their impact on tandem cell efficiencies is reported.
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C7NR07567G
Abstract: Photoexcited carriers are mainly excitons in InGaN/GaN multiple quantum well planar layers while free electron holes are greatly increased in nanorods.
Publisher: IOP Publishing
Date: 10-2012
Abstract: Boron (B)- and antimony (Sb)-doped Si quantum dots (QDs) in Si 3 N 4 films were fabricated using the co-sputtering method with a post-deposition anneal. The effect of B and Sb on Si QDs films was investigated in terms of structural, optical and electrical properties. It is found that a low dopant concentration induced negligible structural changes in the Si QD films. The PL intensity decreases with increasing B or Sb content. This could result from the non-radiative recombination processes attributed to defects associated with the dopants and Auger processes due to successful doping of Si QDs. For the B-doped s le the conductivity increases about 100 times, which could be attributed to an increase in carrier concentration. For the Sb-doped s le, a significant increase (six orders of magnitude) in conductivity suggests an effective Sb doping. The charge transport mechanism in the Sb-doped Si QD films matches well with the percolation-hopping model in low temperature region. Both B- and Sb-doped s les show thermally activated hopping conduction characteristics in the range of 220–320 K.
Publisher: American Chemical Society (ACS)
Date: 31-08-2017
Publisher: Elsevier BV
Date: 11-2017
Publisher: Elsevier BV
Date: 04-2008
Publisher: American Chemical Society (ACS)
Date: 04-03-2020
DOI: 10.1021/JACS.0C00411
Publisher: American Chemical Society (ACS)
Date: 13-02-2018
Publisher: Hindawi Limited
Date: 28-08-2007
DOI: 10.1155/2007/69578
Abstract: We report work progress on the growth of Si quantum dots in different matrices for future photovoltaic applications. The work reported here seeks to engineer a wide-bandgap silicon-based thin-film material by using quantum confinement in silicon quantum dots and to utilize this in complete thin-film silicon-based tandem cell, without the constraints of lattice matching, but which nonetheless gives an enhanced efficiency through the increased spectral collection efficiency. Coherent-sized quantum dots, dispersed in a matrix of silicon carbide, nitride, or oxide, were fabricated by precipitation of Si-rich material deposited by reactive sputtering or PECVD. Bandgap opening of Si QDs in nitride is more blue-shifted than that of Si QD in oxide, while clear evidence of quantum confinement in Si quantum dots in carbide was hard to obtain, probably due to many surface and defect states. The PL decay shows that the lifetimes vary from 10 to 70 microseconds for diameter of 3.4 nm dot with increasing detection wavelength.
Publisher: Wiley
Date: 13-02-2020
Publisher: Wiley
Date: 23-01-2020
Publisher: Elsevier BV
Date: 08-2020
Publisher: Wiley
Date: 19-12-2022
Abstract: The power conversion efficiency (PCE) of solution‐processed organic–inorganic mixed halide perovskite solar cells has achieved rapid improvement. However, it is imperative to minimize the voltage deficit ( W oc = E g / q − V oc ) for their PCE to approach the theoretical limit. Herein, the strategy of depositing homologous bromide salts on the perovskite surface to achieve a surface and bulk passivation for the fabrication of solar cells with high open‐circuit voltage is reported. Distinct from the conclusions given by previous works, that homologous bromides such as FABr only react with PbI 2 to form a large‐bandgap perovskite layer on top of the original perovskite, this work shows that the bromide also penetrates the perovskite film and passivates the perovskite in the bulk. This is confirmed by the small‐bandgap enlargement observed by absorbance and photoluminescence, and the bromide element ratio increasing in the bulk by time‐of‐flight secondary‐ion mass spectrometry and depth‐resolved X‐ray photoelectron spectroscopy. Furthermore, a clear suppression of non‐radiative recombination is confirmed by a variety of characterization methods. This work provides a simple and universal way to reduce the W oc of single‐junction perovskite solar cells and it will also shed light on developing other high‐performance optoelectronic devices, including perovskite‐based tandems and light‐emitting diodes.
Publisher: American Vacuum Society
Date: 11-2000
DOI: 10.1116/1.1318190
Abstract: In this article, we present the fabrication and electrical characterization of nanostructures made of alkanethiol-encapsulated gold particles. We fabricated ordered close-packed monolayer and multilayer structures of encapsulated gold particles using a self-organization process. Room-temperature electrical properties of these nanostructures were studied by using a conductive atomic force microscope. In both cases of monolayer and multilayer structures, the current suppression around zero bias was observed for 9-nm-diameter gold particles. However, it was not observed for 20-nm-diameter particles. This suggests that the Coulomb blockade has occurred in the case of 9-nm-diameter particles. Moreover, the current–voltage properties of multilayer structures demonstrate a nearly linear relation between the Coulomb gap Vg and the number of layers NL, which is in good agreement with the theory of single-electron tunneling in a tunnel-junction array. These electrical properties suggest that an alkanethiol shell on gold particles can serve as a stable tunnel barrier. As a consequence, the proposed method for fabricating quantum dot structures is very useful for developing nanoelectronic devices.
Publisher: IEEE
Date: 06-2016
Publisher: IEEE
Date: 06-2015
Publisher: Springer Science and Business Media LLC
Date: 2001
DOI: 10.1557/PROC-704-W4.5.1/AA4.5.1
Abstract: In this paper we describe fabrication methods for two types of nanostructures, two- and three-dimensional arrays of gold nanoparticles. Large-scale and high-ordered monolayers of alkanethiol-encapsulated gold particles were fabricated by using Langmuir-Blodgett (LB) method. Three-dimensional nanoparticle arrays composed of gold nanoparticles of two different sizes, which were encapsulated by complementary thiol-capped DNA oligonucleotides, were fabricated by using DNA hybridization. DNA hybridization occurred upon mixing these particles, which resulted in the assembly of three-dimensional nanostructure of gold particles. Scanning electron microscopy observations and UV spectroscopy measurement were performed to confirm the construction of the nanostructures.
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1CC13738G
Abstract: The CuInS(2) (CIS) nanoparticles were wrapped uniformly throughout the inner and outer walls of TNTs (TNT) by using square wave pulsed-electrodeposition. This structure enables the CuInS(2)-TiO(2) (CIS-TNT) to exhibit p-n junction diode behavior and enhanced photoelectrochemical properties.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5RA02805A
Abstract: A model is developed to fit the PL spectrum based on spontaneous emission. With this model, we can quantitatively analyse the QD size and its distribution using the PL spectra only, saving the need of time consuming and destructive characterization methods such as TEM.
Publisher: American Physical Society (APS)
Date: 17-10-2014
Publisher: Elsevier BV
Date: 2011
Publisher: AIP Publishing
Date: 07-12-2015
DOI: 10.1063/1.4937270
Abstract: Though Ge crystallization has been widely studied, few works investigate metal-induced crystallization of ultrathin Ge films. For 2 nm Ge films in oxide matrix, crystallization becomes challenging due to easy oxidation and low mobility of Ge atoms. Introducing metal atoms may alleviate these problems, but the functions and the behaviours of metal atoms need to be clarified. This paper investigates the crystallization dynamics of a multilayer structure 1.9 nm Ge/0.5 nm Al/1.5 nm Al2O3 under rapid thermal annealing (RTA). The functions of metal atoms, like effective anti-oxidation, downshifting Raman peaks, and incapability to decrease crystallization temperature, are found and explained. The metal behaviours, such as inter-diffusion and defect generation, are supported with direct evidences, Al-Ge nanobicrystals, and Al cluster in Ge atoms. With these understandings, a two-step RTA process achieves high-quality 2 nm nanocrystal Ge films with Raman peak at 298 cm−1 of FWHM 10.3 cm−1 and atomic smooth interfaces.
Publisher: Technical Association of Photopolymers, Japan
Date: 24-06-2019
Publisher: American Chemical Society (ACS)
Date: 08-06-2021
Publisher: IEEE
Date: 06-2015
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3TC32376E
Abstract: Novel electron transfer results in PL quenching in both graphene oxide–Au 25 and graphene oxide–Au 10 nanocomposites.
Publisher: SPIE
Date: 23-02-2017
DOI: 10.1117/12.2251197
Publisher: American Chemical Society (ACS)
Date: 12-09-2019
DOI: 10.1021/ACS.JPCLETT.9B02423
Abstract: Colloidal quantum dot solids are attractive candidates for tandem solar cells because of their widely tunable bandgaps. However, the development of the quantum dot tandem solar cell has lagged far behind that of its single-junction counterpart. One of the fundamental problems with colloidal quantum dot solar cells is the relatively small diffusion length, which limits the quantum dot absorbing layer thickness and hence the power conversion efficiency. In this research, guided by optical modeling and utilizing a graded band alignment strategy, a two-terminal monolithic solution-processed quantum dot tandem solar cell has been successfully fabricated and a power conversion efficiency of 6.8% has been achieved. The band grading approach utilized the complementary tuning of work functions and band alignment through judicious choices of the nanoparticle surface chemistry and quantum dot confined size. This work demonstrates a general approach to improving the efficiency for tandem thin-film solar cells.
Publisher: American Chemical Society (ACS)
Date: 04-2021
Publisher: Springer Science and Business Media LLC
Date: 2014
DOI: 10.1557/OPL.2014.405
Abstract: For structural investigation, highly (112) oriented tetragonal Cu 2 ZnSnS 4 (CZTS) thin films on hexagonal sapphire (0001) single crystal substrates were obtained by radio frequency (RF) magnetron sputtering. The influences of the deposition parameters, such as substrate temperature (T sub ) and working Ar pressure (P Ar ) on the chemical composition and structural properties of as deposited CZTS films were investigated. The film sputtered at 500°C has the only orientation of (112), also, it bears the best structural quality with pure CZTS phase and an estimated band gap of 1.51eV.
Publisher: Wiley
Date: 19-11-2020
Publisher: Elsevier BV
Date: 08-2010
Publisher: AIP Publishing
Date: 15-06-2009
DOI: 10.1063/1.3148262
Abstract: Tin (Sn) nanocrystals (NCs) embedded in a silicon nitride (Si3N4) matrix have been fabricated in a cosputtering process employing low temperature (100 °C) substrate heating. Transmission electron microscopy (TEM) showed the formation of uniformly sized Sn NCs of 5.2±0.9 nm evenly distributed in the Si3N4 matrix. Both TEM and x-ray diffraction measurements showed that the Sn NCs adopted the semimetallic tetragonal β-Sn structure rather than the cubic semiconducting alpha-Sn structure. X-ray photoelectron spectroscopy revealed that the semimetallic state (Sn0) is the major component of Sn in the s le films. Our investigation demonstrates a pronounced effect of the substrate temperature on the formation of Sn NCs. The mechanism of in situ formation of Sn NCs is discussed. We suggest that the formation of uniformly sized Sn NCs is correlated with lowering the surface mobility of the nuclei due to the presence of the cosputtered Si3N4.
Publisher: Elsevier BV
Date: 10-2011
Publisher: Elsevier BV
Date: 04-2018
Publisher: Japan Soc. Appl. Phys
Date: 2000
Publisher: Wiley
Date: 10-11-2010
DOI: 10.1002/PIP.1045
Publisher: American Chemical Society (ACS)
Date: 11-08-2021
Publisher: AIP Publishing
Date: 03-03-2014
DOI: 10.1063/1.4867093
Abstract: The heteroepitaxy of tetragonal Cu2ZnSnS4 (CZTS) thin films on hexagonal sapphire (0001) single crystal substrates is successfully obtained by radio frequency magnetron sputtering. The sputtered CZTS film has a mirror-like smooth surface with a root mean square roughness of about 5.44 nm. X-ray θ-2θ scans confirm that CZTS film is (112) oriented on sapphire with an out of plane arrangement of CZTS (112) ‖ sapphire (0001). X-ray Phi scan further illustrates an in plane ordering of CZTS [201¯] ‖ sapphire [21¯1¯0]. The high resolution transmission electron microscopy image of the interface region clearly shows that the CZTS thin film epitaxially grows on the sapphire (0001) substrate. The band gap of the film is found to be approximately 1.51 eV.
Publisher: Elsevier BV
Date: 10-2017
DOI: 10.1016/J.JCIS.2017.06.017
Abstract: Cesium lead halide (CsPbX
Publisher: AIP Publishing
Date: 17-06-2013
DOI: 10.1063/1.4811263
Abstract: The performance of hot carrier solar cells has been analyzed using a model incorporating the relaxation times of the relevant electronic processes. The variations in the maximum efficiency as well as the carrier statistics are demonstrated according to different carrier-carrier scattering rates. The significant dependance of cell performances on Coulomb scattering properties is quantitatively demonstrated and explained by carrier depletion, asymmetric electron and hole statistics, and unmatched transmission properties for carrier extraction. The inter-relation between the electronic properties of the absorber material and the contact properties implies that an integrated design with both parts is required.
Publisher: American Chemical Society (ACS)
Date: 08-10-2019
Publisher: American Chemical Society (ACS)
Date: 23-08-2023
Publisher: The Electrochemical Society
Date: 21-03-2011
DOI: 10.1149/1.3567726
Abstract: Fabrication process and quantum confinement effect of Ge multiple quantum wells (MQWs) structure with Si3N4 barriers were investigated for its potential application in 3rd-Generation tandem solar cells. The structure was fabricated by alternating deposition of Ge and Si3N4 layers using magnetron co-sputtering and crystallized by rapid thermal annealing (RTA). The Ge MQWs structures were characterized by X-ray reflection, Raman microscopy and glancing incidence X-ray diffraction. Optical properties were analyzed by transmission and reflection measurements. Above characterizations demonstrated that Ge has formed polycrystalline layers restrained between amorphous Si3N4 barriers after annealing. The crystallization temperature increased with decreasing Ge layer thickness in other words, thicker Ge layer is prone to crystallize. And this Ge layer crystallinity is found to be important in deciding quantum confinement effect achieved in the multilayer structure.
Publisher: American Chemical Society (ACS)
Date: 10-02-2015
DOI: 10.1021/JP512936Z
Publisher: Wiley
Date: 27-11-2021
Abstract: The surface chemistry of colloidal quantum dots (CQD) play a crucial role in fabricating highly efficient and stable solar cells. However, as‐synthesized PbS CQDs are significantly off‐stoichiometric and contain inhomogeneously distributed S and Pb atoms at the surface, which results in undercharged Pb atoms, dangling bonds of S atoms and uncapped sites, thus causing surface trap states. Moreover, conventional ligand exchange processes cannot efficiently eliminate these undesired atom configurations and defect sites. Here, potassium triiodide (KI 3 ) additives are combined with conventional PbX 2 matrix ligands to simultaneously eliminate the undercharged Pb species and dangling S sites via reacting with molecular I 2 generated from the reversible reaction KI 3 ⇌ I 2 + KI. Meanwhile, high surface coverage shells on PbS CQDs are built via PbX 2 and KI ligands. The implementation of KI 3 additives remarkably suppresses the surface trap states and enhances the device stability due to the surface chemistry optimization. The resultant solar cells achieve the best power convention efficiency of 12.1% and retain 94% of its initial efficiency under 20 h continuous operation in air, while the control devices with KI additive deliver an efficiency of 11.0% and retains 87% of their initial efficiency under the same conditions.
Publisher: IEEE
Date: 06-2012
Publisher: American Chemical Society (ACS)
Date: 12-12-2019
DOI: 10.1021/ACS.JPCLETT.9B03210
Abstract: The dynamics of photogenerated carriers and mobile ions in operational cesium lead halide (CsPbI
Publisher: American Association for the Advancement of Science (AAAS)
Date: 19-06-2020
Abstract: Solar cells are subject to heating when operating in sunlight, and the organic components of hybrid perovskite solar cells, especially the commonly used methylammonium cation, can undergo thermal decomposition. Encapsulation can limit decomposition by bringing such reactions to equilibrium and can prevent exposure to damaging ambient moisture. Shi et al. examined several encapsulation schemes for perovskite films and devices by probing volatile products with gas chromatography–mass spectrometry (see the Perspective by Juarez-Perez and Haro). Pressure-tight polymer/glass stack encapsulation was effective in suppressing gas transfer and allowed solar cells containing methylammonium to pass harsh moisture and thermal cycling tests. Science , this issue p. eaba2412 see also p. 1309
Publisher: IOP Publishing
Date: 13-06-2018
Publisher: AIP Publishing
Date: 07-01-2019
DOI: 10.1063/1.5081805
Abstract: Lead halide perovskite nanocrystals (NCs) have rapidly emerged as promising materials for low-cost and high-efficiency photovoltaic, optoelectronic, and photonic devices. The Stokes shift is a crucial parameter affecting their performance. In this work, we find that the external Stokes shift is strongly dependent on photon recycling. Due to the nonlinear nature of the quantum confinement effect (QCE), the bandgap distribution becomes extremely broad when the sizes are ultra-small, resulting in many repetitions of photon recycling and substantial emission redshift. Thereby, the smaller NCs exhibit larger external Stokes shifts. In detail, for the small NCs with the most probable size of 6.4 nm, the intrinsic Stokes shift is about 71 meV, but the observed external Stokes shift becomes 143.4 meV in the concentrated solution, whereas the intrinsic and apparent Stokes shifts are 69 and 97.6 meV for large NCs of 9.7 nm. Therefore, photon recycling significantly contributes to the external Stokes shift of perovskite NCs, in particular for the ultra-small sizes with strong QCE. This finding will add to the growing fundamental physical understanding of perovskites, which is of great interest due to their applications in photovoltaics and other fields.
Publisher: SPIE
Date: 22-12-2015
DOI: 10.1117/12.2202330
Publisher: Elsevier BV
Date: 05-2022
Publisher: Wiley
Date: 13-10-2016
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3TA02565A
Abstract: Our study highlights importance elements of the nanoscale intragrain feature that may pave the way to high-efficiency perovskite solar cells.
Publisher: Wiley
Date: 16-08-2019
Publisher: Elsevier BV
Date: 07-2020
Publisher: American Chemical Society (ACS)
Date: 22-10-2014
DOI: 10.1021/JZ502014R
Abstract: The past two years have seen the uniquely rapid emergence of a new class of solar-cell-based on mixed organic-inorganic halide perovskite. In this work, we demonstrate a promising technique for studying the morphology of perovskite and its impact on carrier extraction by carrier transport layer using one-photon and two-photon fluorescence imaging in conjunction with time-resolved photoluminescence. This technique is not only effective in separating surface and bulk effects but it also allows the determination of lifetimes in localized regions and local carrier extraction efficiency. The difference in sensitivities of transport materials to grain boundaries and film uniformity is highlighted in this study. It is shown that the PCBM fabricated in this work is more sensitive to film nonuniformity, whereas spiro-OMeTAD is more sensitive to grain boundaries in terms of effective carrier extraction.
Publisher: Wiley
Date: 17-04-2021
Publisher: American Chemical Society (ACS)
Date: 16-05-2016
Publisher: American Vacuum Society
Date: 2001
DOI: 10.1116/1.1335678
Abstract: In this article, we present an experimental study of the formation of a Langmuir–Blodgett (LB) monolayer of alkanethiol-encapsulated gold particles. We developed a procedure for preparing the LB spreading suspension from an aqueous gold colloid, and we fabricated a large-scale densely packed monolayer of alkanethiol-encapsulated particles covering an entire substrate using the LB technique. Scanning electron microscopy observations demonstrated that this LB monolayer is composed of domains of ordered close-packed encapsulated gold particles, some of which extended to about 10 μm in extent. A detailed study of the forming mechanism of the LB monolayer of gold particles indicates that the ordered particle domains were formed by a self-organization process induced by the evaporation of the spreading suspension before LB compression. These domains were then aggregated to a densely packed monolayer by the compression process. The proposed method provides a feasible procedure for fabricating a variety of new nanostructured materials.
Publisher: IEEE
Date: 20-06-2021
Publisher: Wiley
Date: 25-02-2019
Publisher: Elsevier BV
Date: 02-2016
Publisher: Elsevier BV
Date: 02-2020
Publisher: American Chemical Society (ACS)
Date: 19-03-2019
Publisher: Elsevier BV
Date: 2011
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5TC03109E
Abstract: The defect density and relaxation rate in organic–inorganic perovskites dominate the carrier recombination dynamics and thus PL intensity exhibits super-linear increase with increasing excitation.
Publisher: MDPI AG
Date: 25-05-2022
DOI: 10.3390/MICROORGANISMS10061095
Abstract: Since the identification of Hendra virus (HeV) infections in horses in Australia in 1994, more than 80 outbreaks in horses have been reported, and four out of seven spillover infections in humans had a fatal outcome. With the availability of a subunit vaccine based on the HeV-Glycoprotein (HeV-G), there is a need to serologically Differentiate the Infected from the Vaccinated Animals (DIVA). We developed an indirect ELISA using HeV-G expressed in Leishmania tarentolae and HeV-Nucleoprotein (HeV-N) expressed in recombinant baculovirus-infected insect cells as antigens. During evaluation, we tested panels of sera from naïve, vaccinated and infected horses that either originated from a Hendra-virus free region, or had been pre-tested in validated diagnostic tests. Our data confirm the reliability of this approach, as HeV-N-specific antibodies were only detected in sera from infected horses, while HeV-G-specific antibodies were detected in infected and vaccinated horses with a high level of specificity and sensitivity. Given the excellent correlation of data obtained for German and Australian HeV-negative horses, we assume that this test can be applied for the testing of horse serum s les from a variety of geographical regions.
Publisher: Springer Science and Business Media LLC
Date: 31-03-2023
DOI: 10.1186/S12983-021-00392-2
Abstract: Worker reproduction has an important influence on the social cohesion and efficiency of social insect colonies, but its role in the success of invasive ants has been neglected. We used observations of 233 captive colonies, laboratory experiments, and genetic analyses to investigate the conditions for worker reproduction in the invasive Anoplolepis gracilipes (yellow crazy ant) and its potential cost on interspecific defence. We determined the prevalence of worker production of males and whether it is triggered by queen absence whether physogastric workers with enlarged abdomens are more likely to be reproductive, how normal workers and physogastric workers compare in their contributions to foraging and defence and whether worker-produced males and males that could have been queen- or worker-produced differ in their size and heterozygosity. Sixty-six of our 233 captive colonies produced males, and in 25 of these, some males could only have been produced by workers. Colonies with more workers were more likely to produce males, especially for queenless colonies. The average number of days between the first appearance of eggs and adult males in our colonies was 54.1 ± 10.2 (mean ± SD, n = 20). In our laboratory experiment, queen removal triggered an increase in the proportion of physogastric workers. Physogastric workers were more likely to have yolky oocytes (37–54.9%) than normal workers (2–25.6%), which is an indicator of fertile or trophic egg production. Physogastric workers were less aggressive during interspecific aggression tests and foraged less than normal workers. The head width and wing length of worker-produced males were on average 4.0 and 4.3% greater respectively than those of males of undetermined source. Our microsatellite DNA analyses indicate that 5.5% of worker-produced males and 14.3% of males of undetermined source were heterozygous, which suggests the presence of diploid males and/or genetic mosaics in A. gracilipes . Our experimental work provides crucial information on worker reproduction in A. gracilipes and its potential cost to colony defence. The ability of A. gracilipes workers to produce males in the absence of queens may also contribute to its success as an invasive species if intranidal mating can take place between virgin queens and worker-produced males.
Publisher: American Chemical Society (ACS)
Date: 17-09-2015
DOI: 10.1021/ACS.JPCLETT.5B01608
Abstract: In this work, the use of a high bandgap perovskite solar cell in a spectrum splitting system is demonstrated. A remarkable energy conversion efficiency of 23.4% is achieved when a CH3NH3PbBr3 solar cell is coupled with a 22.7% efficient silicon passivated emitter rear locally diffused solar cell. Relative enhancements of >10% are demonstrated by CH3NH3PbBr3/CH3NH3PbI3 and CH3NH3PbBr3/multicrystalline-screen-printed-Si spectral splitting systems with tandem efficiencies of 13.4% and 18.8%, respectively. The former is the first demonstration of an all perovskite split spectrum system. The CH3NH3PbBr3 cell on a mesoporous structure was fabricated by the vapor-assisted method while the planar CH3NH3PbI3 cell was fabricated by the gas-assisted method. This work demonstrates the advantage of the higher voltage output from the high bandgap CH3NH3PbBr3 cell and its suitability in a tandem system.
Publisher: Elsevier BV
Date: 09-2017
Publisher: SPIE
Date: 08-09-2015
DOI: 10.1117/12.2187592
Publisher: Wiley
Date: 27-10-2022
Abstract: All‐inorganic CsPbX 3 (X = Cl, Br, I, or mixed halides) perovskite quantum dots (QDs) exhibit tunable optical bandgaps and narrow emission peaks, which have received worldwide interest in the field of both photovoltaics (PVs) and light‐emitting diodes (LEDs). Herein, it is reported a discovery that CsPbI 3 perovskite QD solar cell can simultaneously deliver high PV performance and intense electroluminescence. In specific, the multifunctional CsPbI 3 QD film is fabricated through a simple yet efficient solid‐state‐ligand exchange process using a tailored organic ligand triphenyl phosphite (TPPI). The function of QD surface manipulation using TPPI here is proven to be twofold, balancing the carrier transport and effectively passivating the QD surface to produce conductive and emissive QD film. The CsPbI 3 perovskite QD solar cell delivers a ch ion efficiency of 15.21% with improved open circuit voltage and high fill factor. Concurrently functioning as a red LED, the CsPbI 3 perovskite QD solar cell outputs electric power to light conversion efficiency approaching 4%, a record value for QD electroluminescent PVs. The results here indicate that these versatile perovskite QDs may be a promising candidate for fabricating multifunctional optoelectronic devices.
Publisher: Frontiers Media SA
Date: 12-04-2021
Publisher: Wiley
Date: 17-05-2020
Publisher: Wiley
Date: 17-01-2018
Publisher: IEEE
Date: 12-2012
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8EE00689J
Abstract: A simple and scalable interface-layer free monolithic perovskite/silicon tandem has been demonstrated achieving over 20% efficiency on a large area.
Publisher: American Vacuum Society
Date: 11-2001
DOI: 10.1116/1.1410943
Abstract: A highly ordered monolayer film of alkanethiol-encapsulated gold nanoparticles was fabricated on a silicon substrate by using the Langmuir–Blodgett (LB) method. The effects on the particle order, of the particle concentration and the type of solvent of the LB spreading suspension of encapsulated gold particles, were studied. We found that a low particle concentration of 0.06–0.3 mg/mL in chloroform is optimal for the fabrication of high quality gold particle monolayers. Since the proposed method is not restricted to gold particles, it is believed to be a practical process for fabricating quantum dot structures of various particle sizes and compositions.
Publisher: MDPI AG
Date: 25-10-2023
DOI: 10.3390/EN16217248
Publisher: SPIE
Date: 07-12-2013
DOI: 10.1117/12.2033683
Publisher: Wiley
Date: 15-02-2023
Abstract: Electrospun polyvinylidene fluoride (PVDF) nanofibers have been widely used in the fabrication of flexible piezoelectric sensors and nanogenerators, due to their excellent mechanical properties. However, their relatively low piezoelectricity is still a critical issue. Herein, a new and effective route to enhance the piezoelectricity of PVDF nanofiber mats by electrospraying zinc oxide (ZnO) nanoparticles between layers of PVDF nanofibers is demonstrated. As compared to the conventional way of dispersing ZnO nanoparticles into PVDF solution for electrospinning nanofiber mats, this approach results in multilayered PVDF+ZnO nanofiber mats with significantly increased piezoelectricity. For ex le, 6.2 times higher output is achieved when 100% of ZnO (relative to PVDF quantity) is electrosprayed between PVDF nanofibers. Moreover, this new method enables higher loading of ZnO without having processing challenges and the maximum peak voltage of ≈3 V is achieved, when ZnO content increases up to 150%. Additionally, it is shown that the s les with equal amount of material but consisting of different number of layers have no significant difference. This work demonstrates that the proposed multilayer design provides an alternative strategy to enhance the piezoelectricity of PVDF nanofibers, which can be readily scaled up for mass production.
Publisher: Research Square Platform LLC
Date: 15-09-2020
DOI: 10.21203/RS.3.RS-75982/V1
Abstract: Understanding and engineering exciton transport in quantum dot (QD) solids is both of fundamental interest and crucial to their broad applications in devices 1-6 . Till date, studies of exciton transport in QD solids on pico/nano-second timescales have led to the conclusion that closer packing of QDs enables faster exciton transport, while energetic/structural heterogeneity leads to reduction of exciton diffusivity over time 7,8 . Here we study PbS QD solids using transient absorption microscopy with 13 femtoseconds time resolution and 10 nm spatial precision. We find exciton diffusivities in the range of ~10 2 cm 2 s -1 within the first few hundred femtoseconds after photoexcitation, followed by the transition to a slower transport regime with diffusivities in the range 10 -1 to 1 cm 2 s -1 . Counterintuitively, the initial diffusivity is higher and the time before the transition to the slower transport phase is longer in QD solids with longer ligand lengths. This suggests a transition from early-time transport of delocalized excitons to later time hopping based transport of localized excitons, where QD packing density and heterogeneity accelerate the localization process. Our results reveal a new regime for exciton transport in QD solids and provide design rules to engineer desired transport properties in these systems on a range of timescales.
Publisher: AIP Publishing
Date: 23-01-2017
DOI: 10.1063/1.4974478
Abstract: Inelastic X-ray scattering (IXS) on an In0.17Ga0.83As/GaAs0.8P0.2 multiple quantum well (MQW) superlattice has been conducted to investigate the potential for phonon bottlenecks in low dimensional materials. This work shows that the measured spectra are in good agreement with an adiabatic bond charge model prediction and back-folded phonon modes make large contributions to the broadening of peaks observed in the spectra. The high-lying mode at 45 meV in the MQW is attributed to vibrations of Ga and P and confirmed by both experiment and theory. The acoustic phonons have a dominant contribution from the Ga and As components, and the contribution from InAs is small and only visible at around 29.7 meV. Low energy optical modes resulting from back-folding might be a key to increased electron-phonon coupling in the material system. The suitability of utilizing IXS as a means to investigate phonon modes in low dimensional materials is also discussed.
Publisher: Wiley
Date: 19-10-2011
Publisher: Wiley
Date: 29-11-2022
Abstract: Structural defects are ubiquitous for polycrystalline perovskite films, compromising device performance and stability. Herein, a universal method is developed to overcome this issue by incorporating halide perovskite quantum dots (QDs) into perovskite polycrystalline films. CsPbBr 3 QDs are deposited on four types of halide perovskite films (CsPbBr 3 , CsPbIBr 2 , CsPbBrI 2 , and MAPbI 3 ) and the interactions are triggered by annealing. The ions in the CsPbBr 3 QDs are released into the thin films to passivate defects, and concurrently the hydrophobic ligands of QDs self‐assemble on the film surfaces and grain boundaries to reduce the defect density and enhance the film stability. For all QD‐treated films, PL emission intensity and carrier lifetime are significantly improved, and surface morphology and composition uniformity are also optimized. Furthermore, after the QD treatment, light‐induced phase segregation and degradation in mixed‐halide perovskite films are suppressed, and the efficiency of mixed‐halide CsPbIBr 2 solar cells is remarkably improved to over 11% from 8.7%. Overall, this work provides a general approach to achieving high‐quality halide perovskite films with suppressed phase segregation, reduced defects, and enhanced stability for optoelectronic applications.
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3NR03015F
Abstract: Super-small Au8 nanoclusters have shown great potential to be used in bioimaging, biosensors and catalysis. Understanding the fluorescence origin and the spectral broadening mechanism is of critical importance for the applications. Here we investigate the fluorescence origin and the spectral broadening mechanism using steady state and ultrafast time-resolved spectroscopy. For the first time we clearly elucidate the broad fluorescence of Au8 nanoclusters consisting of an intrinsic band from the Au8 core and an extrinsic band from the surface fluorophores. The emission energy of the intrinsic band is in accord with the rule of E/N(1/3) and the spectral broadening originates from ultrafast dephasing due to effective electron-electron scattering. The extrinsic band has a much larger bandwidth due to massive surface fluorophores it is the dominant mechanism for spectral broadening in Au8. In contrast to the jellium model predictions, the overall fluorescence exhibits excitation wavelength dependence.
Publisher: IOP Publishing
Date: 25-04-2019
Abstract: Cs
Publisher: IEEE
Date: 06-2017
Publisher: American Chemical Society (ACS)
Date: 24-01-2017
Publisher: American Chemical Society (ACS)
Date: 14-04-2021
Publisher: American Chemical Society (ACS)
Date: 29-04-2020
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C7TC05366E
Abstract: Solar cells fabricated using modified AgBiS 2 nanocrystals achieved a PCE of 4.3%, which is a 30% improvement compared with conventional AgBiS 2 nanocrystal solar cells.
Publisher: Elsevier BV
Date: 2018
DOI: 10.1016/J.JCIS.2017.09.080
Abstract: Type-II quantum dots (QDs) are emerging as a promising candidate for full color light sources owing to their advantages in achieving full color light by tuning the heterostructures. Despite the recent developments in type-II QDs, the choices of proper materials are limited for the composition of a high-quality QD and it still remains a big challenge to enhance the photoluminescence (PL) quantum yields (QYs) of type-II QDs for light-emitting diode (LED) applications. Here, we develop Cd
Publisher: Wiley
Date: 06-11-2018
Publisher: IOP Publishing
Date: 12-1998
DOI: 10.1143/JJAP.37.7198
Abstract: We have studied a fabrication strategy for self-organization of a two-dimensional array of alkanethiol-encapsulated gold nanodots. The fabrication process has two steps: (1) preparation of alkanethiol-encapsulated gold particles from gold colloidal particles (2) self-organization of an ordered close-packed array of gold nanodots encapsulated by alkanethiol on a substrate. By this method, we succeeded in fabricating a wide range of ordered close-packed monolayers of gold nanodots. The simplicity, flexibility, and practicality of this method makes it a prospective procedure for developing future nanoelectronic devices.
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8CE00728D
Abstract: Improvements in charge carrier transport and equivalent photoluminescence were obtained for CuInS 2 nanoparticles with Ag-surface termination in photovoltaic devices.
Publisher: American Chemical Society (ACS)
Date: 18-04-2018
Abstract: The electron-blocking layer (EBL) is important to balance the charge carrier transfer and achieve highly efficient quantum dot light-emitting diodes (QLEDs). Here, we report the utilization of a soluble tert-butyldimethylsilyl chloride-modified poly( p-phenylene benzobisoxazole) (TBS-PBO) as an EBL for simultaneous good charge carrier transfer balance while maintaining a high current density. We show that the versatile TBS-PBO blocks excess electron injection into the quantum dots (QDs), thus leading to better charge carrier transfer balance. It also restricts the undesired QD-to-EBL electron-transfer process, which preserves the superior emission capabilities of the emitter. As a consequence, the TBS-PBO device delivers an external quantum efficiency (EQE) maximum of 16.7% along with a remarkable current density as high as 139 mA/cm
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5NR07993D
Abstract: PL decay traces (left) and fluorescence lifetime imaging microscopy (FLIM) image (right) of 2 weeks air stored perovskite film.
Publisher: Korean Physical Society
Date: 04-2017
DOI: 10.3938/JKPS.71.968
Publisher: AIP Publishing
Date: 27-11-2002
DOI: 10.1063/1.1518758
Abstract: We present an in situ study on the dispersibility of gold nanoparticles in different solvents by comparing the measured optical absorption spectra to the calculated absorption. Both uncapped and capped particles dispersed in a variety of solvents are investigated. In organic solvents such as chloroform and alcohols, dodecanethiol-capped particles can be dissolved better and with more stability than uncapped nanoparticles. The results of this work demonstrate that surface capping with alkanethiol molecules can dramatically improve the dispersibility of gold nanoparticles in organic solvents. The dissolution nature of the capper and the solvent dominate the dispersibility. We propose a useful method for selecting solvents in order to achieve a high dispersibility of nanoparticle solutions.
Publisher: Elsevier BV
Date: 2014
Publisher: Elsevier BV
Date: 04-2019
Publisher: No publisher found
Date: 2021
Publisher: American Chemical Society (ACS)
Date: 29-08-2022
Publisher: IEEE
Date: 12-2012
Publisher: Wiley
Date: 02-02-2016
Publisher: American Chemical Society (ACS)
Date: 15-09-2020
Publisher: American Chemical Society (ACS)
Date: 22-08-2016
Publisher: SPIE
Date: 22-12-2015
DOI: 10.1117/12.2202420
Publisher: Elsevier BV
Date: 04-2018
Publisher: Wiley
Date: 27-11-2020
Abstract: Perovskite solar cell performance is closely related to the quality of the perovskite absorbing layer which is highly dependent on deposition processes. Sequential process is shown to be effective in fabricating both single‐junction and tandem solar cells delivering comparable efficiencies compared with devices by a single‐step process. Sequence processes exhibit the benefits of controlling crystallization speed, overcoming solvent incompatibility, and greater flexibility. Here, mechanisms of film formation in two common sequential solution processes, namely chemical bath deposition and sequential spin coating, showing that film formation is highly dependent on precursors or deposition conditions, are reviewed. Herein, further review is conducted on how three main strategies improve perovskite crystallization. The first is by PbI 2 complex formation or via intramolecular exchange which is shown to result in a better perovskite conversion and a more ordered perovskite growth. The second strategy is by changing the condition of perovskite precursors, e.g., by solvent, cation, halide, and additive engineering. The last strategy is by altering precursor dispensing conditions and adding vapor or solvent annealing, thereby affecting reaction conditions. Many of these strategies are demonstrated to improve perovskite film morphology with reduced defects.
Publisher: American Chemical Society (ACS)
Date: 24-02-2015
DOI: 10.1021/ACS.JPCLETT.5B00182
Abstract: The past 2 years have seen the uniquely rapid emergence of a new class of solar cell based on mixed organic-inorganic halide perovskite. Grain boundaries are present in polycrystalline thin film solar cell, and they play an important role that could be benign or detrimental to solar-cell performance. Here we present efficient charge separation and collection at the grain boundaries measured by KPFM and c-AFM in CH3NH3PbI3 film in a CH3NH3PbI3/TiO2/FTO/glass heterojunction structure. We observe the presence of a potential barrier along the grain boundaries under dark conditions and higher photovoltage along the grain boundaries compare to grain interior under the illumination. Also, c-AFM measurement presents higher short-circuit current collection near grain boundaries, confirming the beneficial roles grain boundaries play in collecting carriers efficiently.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5RA13499D
Abstract: High resolution of EDX image shows the bromine located on same position of PbS quantum dot.
Publisher: Wiley
Date: 14-11-2017
Publisher: AIP Publishing
Date: 03-04-2023
DOI: 10.1063/5.0127896
Abstract: The microwave annealing of semiconductor devices has not been extensively researched and is rarely utilized in industry, yet it has the potential to significantly reduce the time and cost associated with large-volume semiconductor processing, such as the various heating and annealing processes required in the manufacture of photovoltaic modules. In this paper, we describe microwave annealing of silicon solar cells, the effective passivation of light-induced defects, and a reduction in light-induced degradation. We find that silicon solar cells are heated rapidly in a microwave field and that effective B–O defect passivation can be achieved by microwave processing in less than 2 s. Microwave annealing yields similar results as compared to rapid thermal annealing.
Publisher: Wiley
Date: 04-06-2015
DOI: 10.1002/JRS.4727
Publisher: Elsevier BV
Date: 08-2009
Publisher: IEEE
Date: 06-2010
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6RA20165B
Abstract: PbS QDs are studied as attractive candidates to be applied as hot carrier solar cell absorbers.
Publisher: SPIE
Date: 26-09-2016
DOI: 10.1117/12.2242401
Publisher: SPIE
Date: 02-01-2017
DOI: 10.1117/12.2283318
Publisher: Elsevier BV
Date: 12-2018
Publisher: American Chemical Society (ACS)
Date: 31-08-2018
Publisher: SPIE
Date: 17-10-2014
DOI: 10.1117/12.2067926
Publisher: Springer Science and Business Media LLC
Date: 19-07-2021
DOI: 10.1038/S41598-021-94354-7
Abstract: Photoluminescent materials are advanced cutting-edge heat-rejecting materials capable of reemitting a part of the absorbed light through radiative/non-thermal recombination of excited electrons to their ground energy state. Photoluminescent materials have recently been developed and tested as advanced non-white heat-rejecting materials for urban heat mitigation application. Photoluminescent materials has shown promising cooling potential for urban heat mitigation application, but further developments should be made to achieve optimal photoluminescence cooling potential. In this paper, an advanced mathematical model is developed to explore the most efficient methods to enhance the photoluminescence cooling potential through estimation of contribution of non-radiative mechanisms. The non-radiative recombination mechanisms include: (1) Transmission loss and (2) Thermal losses including thermalization, quenching, and Stokes shift. The results on transmission and thermal loss mechanisms could be used for systems solely relying on photoluminescence cooling, while the thermal loss estimations can be helpful to minimize the non-radiative losses of both integrated photoluminescent-near infrared (NIR) reflective and stand-alone photoluminescent systems. As per our results, the transmission loss is higher than thermal loss in photoluminescent materials with an absorption edge wavelength ( λ AE ) shorter than 794 nm and quantum yield ( QY ) of 50%. Our predictions show that thermalization loss overtakes quenching in photoluminescent materials with λ AE longer than 834 nm and QY of 50%. The results also show that thermalization, quenching, and Stokes shift constitute around 56.8%, 35%, and 8.2% of the overall thermal loss. Results of this research can be used as a guide for the future research to enhance the photoluminescence cooling potential for urban heat mitigation application.
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3NR01998E
Abstract: All-Si tandem solar cells based on Si quantum dots (QDs) are a promising approach to future high-performance, thin film solar cells using abundant, stable and non-toxic materials. An important prerequisite to achieve a high conversion efficiency in such cells is the ability to control the geometry of the Si QD network. This includes the ability to control both, the size and arrangement of Si QDs embedded in a higher bandgap matrix. Using plasmon tomography we show the size, shape and density of Si QDs, that form in Si rich oxide (SRO)/SiO2 multilayers upon annealing, can be controlled by varying the SRO stoichiometry. Smaller, more spherical QDs of higher densities are obtained at lower Si concentrations. In richer SRO layers ellipsoidal QDs tend to form. Using electronic structure calculations within the effective mass approximation we show that ellipsoidal QDs give rise to reduced inter-QD coupling in the layer. Efficient carrier transport via mini-bands is in this case more likely across the multilayers provided the SiO2 spacer layer is thin enough to allow coupling in the vertical direction.
Publisher: AIP Publishing
Date: 15-03-2011
DOI: 10.1063/1.3561439
Abstract: A spectroscopic ellipsometry compatible approach is reported for the optical study of Si quantum dots (QDs) in Si-rich nitride/silicon nitride (SRN/Si3N4) superlattice, which based on Tauc-Lorentz model and Bruggeman effective medium approximation. It is shown that the optical constants and dielectric functions of Si QDs are strongly size dependent. The suppressed imaginary dielectric function of Si QDs exhibits a single broad peak analogous to amorphous Si, which centered between the transition energies E1 and E2 of bulk crystalline Si and blue shifted toward E2 as the QD size reduced. A bandgap expansion observed by the TL model when the size of Si QD reduced is in good agreement with the PL measurement. The bandgap expansion with the reduction of Si QD size is well supported by the first-principles calculations based on quantum confinement.
Publisher: IOP Publishing
Date: 09-2011
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7NR05247B
Abstract: The carrier dynamics of lead sulphide quantum dot (PbS QD) drop cast films and closely packed ordered Langmuir–Blodgett films are studied with ultra-fast femtosecond transient absorption spectroscopy.
Publisher: IOP Publishing
Date: 04-1999
DOI: 10.1143/JJAP.38.L473
Abstract: Experimental studies on the control of the interdot space and the dot size in a self-organized two-dimensional array of gold colloidal nanoparticles encapsulated by alkanethiol are presented. We succeeded in fabricating an ordered close-packed monolayer of gold nanodots of 5 nm as well as 10 nm in diameter. In addition, by changing the length of the alkanethiol molecules, close-packed gold nanodot monolayers with different interdot spaces were formed. The results of this study indicate a linear relationship between the interdot space and the length of the alkanethiol molecule, which demonstrates that the interdot space can be easily controlled by altering alkanethiol molecules.
Publisher: American Chemical Society (ACS)
Date: 06-05-2016
Publisher: Springer Science and Business Media LLC
Date: 07-03-2022
Publisher: Wiley
Date: 29-03-2020
Publisher: Wiley
Date: 03-12-2016
Publisher: SPIE
Date: 02-01-2017
DOI: 10.1117/12.2283328
Publisher: Elsevier BV
Date: 10-2020
Publisher: AIP Publishing
Date: 23-03-2015
DOI: 10.1063/1.4916090
Abstract: Despite that Tauc plot extrapolation has been widely adopted for extracting bandgap energies of semiconductors, there is a lack of theoretical support for applying it to nanocrystals. In this paper, direct-allowed optical transitions in semiconductor nanocrystals have been formulated based on a purely theoretical approach. This result reveals a size-dependant transition of the power factor used in Tauc plot, increasing from one half used in the 3D bulk case to one in the 0D case. This size-dependant intermediate value of power factor allows a better extrapolation of measured absorption data. Being a material characterization technique, the generalized Tauc extrapolation gives a more reasonable and accurate acquisition of the intrinsic bandgap, while the unjustified purpose of extrapolating any elevated bandgap caused by quantum confinement is shown to be incorrect.
Publisher: Elsevier BV
Date: 11-2013
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C7TA11154A
Abstract: Partial replacement of Pb in CsPbI 3 perovskite solar cells with Ca enhances power conversion efficiency to 13.5% under reverse scan (stabilised at 13.3%), without sacrificing stability.
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9CP03059J
Abstract: Halide perovskite materials are excellent light harvesters that have generated enormous interest for photovoltaic technology and an increasing number of other optoelectronic applications.
Publisher: AIP Publishing
Date: 02-02-2017
DOI: 10.1063/1.4975408
Abstract: Silicon nanocrystals embedded in a dielectric matrix have been considered a potential candidate for many optoelectronic and photovoltaic applications and have been under vigorous study in recent years. One of the main properties of interest in this application is the absorption bandgap, which is determined by the quantum confinement of silicon nanocrystals. The ability to predict the absorption bandgap is a key step in designing an optimum solar cell using this material. Although several higher level algorithms are available to predict the electronic confinement in these nanocrystals, most of them make regular-shape assumptions for the ease of computation. In this work, we present a model for the accurate prediction of the quantum confinement in silicon nanocrystals of non-regular shape by employing an efficient, self-consistent Full-Multi-Grid method. Confined energies in spherical, elongated, and arbitrarily shaped nanocrystals are calculated. The excited level calculations quantify the wavefunction coupling and energy level splitting arising due to the proximity of dots. The splitting magnitude was found to be as high as 0.1 eV for the 2 nm size silicon quantum dots. The decrease in confinement energy due to the elongation of dots was found to be more than 0.2 eV, and the trend was similar for different dielectric materials. Theoretical predictions were compared to the results from optical and structural characterisation and found to be in agreement. The loss of degeneracy in highly asymmetric quantum dots, such as a “horse-shoe” shaped quantum dot, significantly affects the excited state energies.
Publisher: IOP Publishing
Date: 2001
DOI: 10.1143/JJAP.40.346
Abstract: The preparation of well-size-controlled colloidal gold nanoparticles in organic solvent is presented. After the preparation of well-size-controlled aqueous colloidal gold particles, we changed the solvent to an organic one. This technique is required to enable a chemical reaction between gold particles and hydrophobic molecules, since a colloidal gold solution is typically prepared in water using a reduction process. We also investigated the stability of the gold particle suspension, and found that the stability decreases in the sequence of water, ethanol, chloroform, and benzene solution.
Publisher: Wiley
Date: 18-09-0044
Abstract: Colloidal quantum dots (QDs) are promising candidate materials for photovoltaics (PV) owing to the tunable bandgap and low-cost solution processability. Lead selenide (PbSe) QDs are particularly attractive to PV applications due to the efficient multiple-exciton generation and carrier transportation. However, surface defects arising from the oxidation of the PbSe QDs have been the major limitation for their development in PV. Here, a new passivation method for chlorinated PbSe QDs via ion exchange with cesium lead halide (Br, I) perovskite nanocrystals is reported. The surface chloride ions on the as-synthesized QDs can be partially exchanged with bromide or iodide ions from the perovskite nanocrystals, hence forming a hybrid halide passivation. Consistent with the improved photoluminescence quantum yield, the ch ion PV device fabricated with these PbSe QDs achieves a PCE of 8.2%, compared to 7.3% of that fabricated with the untreated QDs. This new method also leads to devices with excellent air-stability, retaining at least 93% of their initial PCEs after being stored in ambient conditions for 57 d. This is considered as the first reported PbSe QD solar cell with a PCE of over 8% to date.
Publisher: American Chemical Society (ACS)
Date: 16-12-2019
Abstract: Tandem cells are one of the most effective ways of breaking the single junction Shockley-Queisser limit. Solution-processable phosphate-buffered saline (PbS) quantum dots are good candidates for producing multiple junction solar cells because of their size-tunable band gap. The intermediate recombination layer (RL) connecting the subcells in a tandem solar cell is crucial for device performance because it determines the charge recombination efficiency and electrical resistance. In this work, a solution-processed ultrathin NiO and Ag nanoparticle film serves as an intermediate layer to enhance the charge recombination efficiency in PbS QD dual-junction tandem solar cells. The ch ion devices with device architecture of indium tin oxide/S-ZnO/1.45 eV PbS-PbI
Publisher: American Chemical Society (ACS)
Date: 11-09-2017
Publisher: Elsevier BV
Date: 04-2017
Publisher: Japan Society of Applied Physics
Date: 1999
Publisher: SPIE
Date: 07-12-2013
DOI: 10.1117/12.2035308
Publisher: American Chemical Society (ACS)
Date: 30-01-2004
DOI: 10.1021/LA0302293
Abstract: The effects of the surface pressure on the particle arrangement of Langmuir-Blodgett (LB) monolayers of alkanethiol-capped gold nanoparticles were studied. The LB monolayers were prepared from a highly concentrated particle solution, which increases film fabrication efficiency but readily causes small particle voids in the particle array. Overcompressing the LB monolayer to a high surface pressure restructured the particles and eliminated the voids. When the gold particles capped by dodecanethiol were 8.5 nm in diameter, the particle arrangement was vastly improved and a wafer-scale LB monolayer was transferred onto a substrate at the surface pressure of 20 mN/m.
Publisher: Elsevier BV
Date: 2012
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6TC03206K
Abstract: Both reversible and irreversible PL responses can be induced by an electric field and establish a negative feedback.
Publisher: IEEE
Date: 12-2014
Publisher: Elsevier BV
Date: 08-2021
Publisher: Springer Science and Business Media LLC
Date: 2014
DOI: 10.1557/OPL.2014.271
Abstract: In this work, sulfurizing metal precursors prepared by magnetron sputtering was applied in Cu 2 ZnSnS 4 (CZTS) thin film fabrication. Three precursor structures, namely substrate/ Zn/(Cu& Sn), substrate/Zn/Cu/Sn/Cu and substrate/Zn/Sn/Cu, were compared for their synthesized CZTS film quality. It is notable that CZTS film made of the precursor structure of substrate/Zn/(Cu& Sn) has the best film quality with no obvious voids and biggest average grain size. When applying this precursor structure into device fabrication, a working CZTS device with an efficiency of 2.26% was made. The impact of metal precursors on the structural property of CZTS film were characterised by SEM, XRD, Raman and TEM. Thick MoS 2 interfacial layer (∼200nm) between absorber and back Mo contact and ZnS formed in the front and back absorber regions are the possible reasons limiting short-circuit current and fill factor of the cell.
Publisher: Springer Science and Business Media LLC
Date: 20-01-2021
DOI: 10.1038/S41467-020-20749-1
Abstract: All-inorganic CsPbI 3 perovskite quantum dots have received substantial research interest for photovoltaic applications because of higher efficiency compared to solar cells using other quantum dots materials and the various exciting properties that perovskites have to offer. These quantum dot devices also exhibit good mechanical stability amongst various thin-film photovoltaic technologies. We demonstrate higher mechanical endurance of quantum dot films compared to bulk thin film and highlight the importance of further research on high-performance and flexible optoelectronic devices using nanoscale grains as an advantage. Specifically, we develop a hybrid interfacial architecture consisting of CsPbI 3 quantum dot/PCBM heterojunction, enabling an energy cascade for efficient charge transfer and mechanical adhesion. The ch ion CsPbI 3 quantum dot solar cell has an efficiency of 15.1% (stabilized power output of 14.61%), which is among the highest report to date. Building on this strategy, we further demonstrate a highest efficiency of 12.3% in flexible quantum dot photovoltaics.
Publisher: SPIE
Date: 22-12-2015
DOI: 10.1117/12.2202176
Publisher: American Chemical Society (ACS)
Date: 06-12-2017
Publisher: IEEE
Date: 06-2012
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2016
Publisher: Elsevier BV
Date: 04-2015
Publisher: Wiley
Date: 27-05-2016
Publisher: IEEE
Date: 06-2018
Publisher: IOP Publishing
Date: 07-2005
DOI: 10.1143/JJAP.44.5289
Abstract: A simple fabrication process is presented for highly-ordered, highly-oriented carbon nanotube and nanorod arrays by filling alumina nanohole templates with a carbon precursor, polyacrylonitrile (PAN). X-ray photoelectron spectra analysis indicates that PAN changes its chemical structure to sp 2 C–C structure after carbonization at 600°C. Raman characterization of the resulting carbon nanostructure demonstrates a high quality graphite structure. The proposed method may be used to develop carbon nanostructure-based devices.
Publisher: Wiley
Date: 25-10-2023
Abstract: In recent years, wearable sensors and energy harvesters have shown great potential for a wide range of applications in personalized healthcare, robotics, and human–machine interfaces. Among different types of materials used in wearable electronics, piezoelectric materials have gained enormous attention due to their exclusive ability to harvest energy from ambient sources. Piezoelectric materials can be utilized as sensing elements in wearable sensors while harvesting biomechanical energy. Electrospun piezoelectric polymer nanofibers are extensively investigated due to their high flexibility, ease of processing, biocompatibility, and higher piezoelectric property (in contrast to their corresponding cast films). However, as compared to piezoceramic materials, they mostly exhibit relatively lower piezoelectric coefficients. Therefore, considerable efforts have been devoted to improving the piezoelectricity of electrospun polymer nanofibers recently, resulting in significant advances. This review presents a broad overview of these advances including new material, structure designs as well as new strategies to enhance piezoelectricity of electrospun polymer nanofibers. The challenges in achieving high mechanical performance as well as high piezoelectricity are particularly discussed. The main motivation of this review is to examine these challenges and highlight effective approaches to achieving high‐performance piezoelectric sensors and energy harvesters for wearable technologies.
Publisher: American Chemical Society (ACS)
Date: 20-11-2019
Abstract: Electrically conductive polymer/rGO (reduced graphene oxide) films based on styrene and
Publisher: Elsevier BV
Date: 06-2011
Publisher: Elsevier BV
Date: 2020
Publisher: Elsevier BV
Date: 07-2021
Publisher: Elsevier BV
Date: 08-2021
Publisher: IOP Publishing
Date: 12-2020
Abstract: Flexible Cu 2 ZnSn(S,Se) 4 (CZTSSe) solar cells show great potential applications due to low-cost, nontoxicity, and stability. The device performances under an especial open circuit voltage ( V OC ) are limited by the defect recombination of CZTSSe/CdS heterojunction interface. We improve the deposition technique to obtain compact CdS layers without any pinholes for flexible CZTSSe solar cells on Mo foils. The efficiency of the device is improved from 5.7% to 6.86% by highquality junction interface. Furthermore, aiming at the S loss of CdS film, the S source concentration in deposition process is investigated to passivate the defects and improve the CdS film quality. The flexible Mo-foil-based CZTSSe solar cells are obtained to possess a 9.05% efficiency with a V OC of 0.44 V at an optimized S source concentration of 0.68 mol/L. Systematic physical measurements indicate that the S source control can effectively suppress the interface recombination and reduce the V OC deficit. For the CZTSSe device bending characteristics, the device efficiency is almost constant after 1000 bends, manifesting that the CZTSSe device has an excellent mechanical flexibility. The effective improvement strategy of CdS deposition is expected to provide a new perspective for promoting the conversion efficiency of CZTSSe solar cells.
Publisher: Springer Science and Business Media LLC
Date: 22-07-2015
DOI: 10.1038/SREP12469
Abstract: Luminescent silicon nanocrystals (Si NCs) have attracted tremendous research interest. Their size dependent photoluminescence (PL) shows great promise in various optoelectronic and biomedical applications and devices. However, it remains unclear why the exciton emission is limited to energy below 2.1 eV, no matter how small the nanocrystal is. Here we interpret a nanosecond transient yellow emission band at 590 nm (2.1 eV) as a critical limit of the wavelength tunability in colloidal silicon nanocrystals. In the “large size” regime (d ~3 nm), quantum confinement dominantly determines the PL wavelength and thus the PL peak blue shifts upon decreasing the Si NC size. In the “small size” regime (d ~2 nm) the effect of the yellow band overwhelms the effect of quantum confinement with distinctly increased nonradiative trapping. As a consequence, the photoluminescence peak does not exhibit any additional blue shift and the quantum yield drops abruptly with further decreasing the size of the Si NCs. This finding confirms that the PL originating from the quantum confined core states can only exist in the red/near infrared with energy below 2.1 eV while the blue/green PL originates from surface related states and exhibits nanosecond transition.
Publisher: Springer Science and Business Media LLC
Date: 20-07-2020
Publisher: American Chemical Society (ACS)
Date: 06-12-2021
Publisher: American Chemical Society (ACS)
Date: 24-01-2018
Publisher: American Chemical Society (ACS)
Date: 09-08-2017
Publisher: Elsevier BV
Date: 07-2016
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C8TC06495D
Abstract: PbSe quantum dots are mixed into PbS quantum dots to form mixed quantum dots for enhancing device performance in optoelectronic applications due to improved charge mobility in solid films.
Publisher: Elsevier BV
Date: 02-2015
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3TC32395A
Publisher: Elsevier BV
Date: 11-2020
Publisher: Elsevier BV
Date: 10-2019
Publisher: Wiley
Date: 13-07-2017
Publisher: Wiley
Date: 23-11-2023
Abstract: Solution processable semiconductors like organics and emerging lead halide perovskites (LHPs) are ideal candidates for photovoltaics combining high performance and flexibility with reduced manufacturing cost. Moreover, the study of hybrid semiconductors would lead to advanced structures and deep understanding that will propel this field even further. Herein, a novel device architecture involving block copolymer erovskite hybrid bulk heterointerfaces is investigated, such a modification could enhance light absorption, create an energy level cascade, and provides a thin hydrophobic layer, thus enabling enhanced carrier generation, promoting energy transfer and preventing moisture invasion, respectively. The resulting hybrid block copolymer erovskite solar cell exhibits a ch ion efficiency of 24.07% for 0.0725 cm 2 ‐sized devices and 21.44% for 1 cm 2 ‐sized devices, respectively, together with enhanced stability, which is among the highest reports of organic erovskite hybrid devices. More importantly, this approach has been effectively extended to other LHPs with different chemical compositions like MAPbI 3 and CsPbI 3 , which may shed light on the design of highly efficient block copolymer erovskite hybrid materials and architectures that would overcome current limitations for realistic application exploration.
Publisher: Wiley
Date: 02-06-2020
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8TC03599G
Abstract: The antimony-doped tin oxide buffer layer greatly improve the extraction of carriers in a PbSe QD solar cell.
Publisher: IOP Publishing
Date: 05-2001
DOI: 10.1143/JJAP.40.L521
Abstract: DNA oligonucleotides are considered to be as a useful tool for fabricating complex structures on a nanometer scale because of their selective reactivity. Herein, we describe a fabrication technique for heterogeneous three-dimensional nanoparticle arrays composed of gold nanoparticles of two different sizes linked by thiol-synthesized DNA oligonucleotides. Each size of the gold nanoparticles was encapsulated by complementary DNA oligonucleotides. DNA hybridization occurs upon their mixing, resulting in the construction of a three-dimensional nanostructure. Scanning electron microscope (SEM) observation and UV spectroscopy were performed to confirm the construction of the nanostructure. This fabrication technique will be crucial for the advancement of nanotechnology in the next ten years.
Publisher: Elsevier BV
Date: 09-2019
Publisher: American Chemical Society (ACS)
Date: 02-2016
Publisher: IEEE
Date: 1998
Publisher: Elsevier BV
Date: 12-2015
Publisher: Wiley
Date: 10-11-2021
Publisher: IOP Publishing
Date: 26-11-2014
Publisher: American Chemical Society (ACS)
Date: 16-08-2022
Publisher: Wiley
Date: 27-12-2018
Abstract: Hybrid halide perovskite is one of the promising light absorber and is intensively investigated for many optoelectronic applications. Here, the first prototype of a self-powered inorganic halides perovskite for chemical gas sensing at room temperature under visible-light irradiation is presented. These devices consist of porous network of CsPbBr
Publisher: Elsevier BV
Date: 02-2015
Publisher: Elsevier
Date: 2019
Publisher: Elsevier BV
Date: 12-2019
Publisher: Elsevier BV
Date: 12-2020
Publisher: American Chemical Society (ACS)
Date: 10-02-2017
Abstract: We identify nanoscale spatial distribution of PbI
Publisher: Wiley
Date: 19-04-2021
Abstract: Organic‐inorganic hybrid film using conjugated materials and quantum dots (QDs) are of great interest for solution‐processed optoelectronic devices, including photovoltaics (PVs). However, it is still challenging to fabricate conductive hybrid films to maximize their PV performance. Herein, for the first time, superior PV performance of hybrid solar cells consisting of CsPbI 3 perovskite QDs and Y6 series non‐fullerene molecules is demonstrated and further highlights their importance on hybrid device design. In specific, a hybrid active layer is developed using CsPbI 3 QDs and non‐fullerene molecules, enabling a type‐II energy alignment for efficient charge transfer and extraction. Additionally, the non‐fullerene molecules can well passivate the QDs, reducing surface defects and energetic disorder. The ch ion CsPbI 3 QD/Y6‐F hybrid device has a record‐high efficiency of 15.05% for QD/organic hybrid PV devices, paving a new way to construct solution‐processable hybrid film for efficient optoelectronic devices.
Publisher: IEEE
Date: 06-2015
Publisher: SPIE
Date: 16-02-2017
DOI: 10.1117/12.2249931
Publisher: Springer Science and Business Media LLC
Date: 25-01-2019
DOI: 10.1038/S41467-019-08364-1
Abstract: Organic–inorganic metal halide perovskites have gained considerable attention for next-generation photovoltaic cells due to rapid improvement in power conversion efficiencies. However, fundamental understanding of underlying mechanisms related to light- and bias-induced effects at the nanoscale is still required. Here, structural variations of the perovskites induced by light and bias are systematically investigated using scanning probe microscopy techniques. We show that periodically striped ferroelastic domains, spacing between 40 to 350 nm, exist within grains and can be modulated significantly under illumination as well as by electric bias. Williamson-Hall analysis of X-ray diffraction results shows that strain disorder is induced by these applied external stimuli. We show evidence that the structural emergence of domains can provide transfer pathways for holes to a hole transport layer with positive bias. Our findings point to potential origins of I – V hysteresis in halide perovskite solar cells.
Publisher: Wiley
Date: 16-04-2018
Publisher: American Chemical Society (ACS)
Date: 19-02-2016
Abstract: Here, we investigate photoluminescence (PL) and time-resolved photoluminescence (TRPL) in CH3NH3PbBr3 perovskite under continuous illumination, using optical and electro-optical techniques. Under continuous excitation at constant intensity, PL intensity and PL decay (carrier recombination) exhibit excitation intensity dependent reductions in the time scale of seconds to minutes. The enhanced nonradiative recombination is ascribed to light activated negative ions and their accumulation which exhibit a slow dynamics in a time scale of seconds to minutes. The observed result suggests that the organic-inorganic hybrid perovskite is a mixed electronic-ionic semiconductor. The key findings in this work suggest that ions are photoactivated or electro-activated and their accumulation at localized sites can result in a change of carrier dynamics. The findings are therefore useful for the understanding of instability of perovskite solar cells and shed light on the necessary strategies for performance improvement.
Publisher: IEEE
Date: 12-2012
Publisher: AIP Publishing
Date: 12-2007
DOI: 10.1063/1.2817902
Abstract: Sn-based nanocrystals were prepared by depositing Sn-rich SiO2 films using a cosputtering process and a subsequent vacuum annealing. Transmission electron microscopy (TEM) and x-ray diffraction showed formation of Sn nanocrystals evenly distributed in SiO2 matrix at relatively low annealing temperature of 400°C. The size of Sn nanocrystals increased with increasing annealing temperature. X-ray photoelectron spectroscopy revealed that Sn was partially oxidized during the cosputtering process forming Sn oxide nanoclusters of 3.4±0.6nm in diameter after annealing, as observed by TEM. The Sn-based nanocrystal films exhibited wide optical bandgap around 4.2–4.4eV and a slightly high-energy shift with increasing annealing temperature. This result is in close agreement with the absorption in the Sn oxide nanoclusters as well as Sn-related oxygen defects in the matrix.
Publisher: Wiley
Date: 05-02-2020
Start Date: 2022
End Date: 12-2023
Amount: $738,750.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2014
End Date: 11-2019
Amount: $403,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 07-2023
End Date: 06-2026
Amount: $566,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 07-2021
End Date: 12-2023
Amount: $699,664.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2023
End Date: 12-2023
Amount: $480,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 04-2016
End Date: 12-2019
Amount: $370,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 02-2022
End Date: 02-2025
Amount: $455,110.00
Funder: Australian Research Council
View Funded Activity