ORCID Profile
0000-0001-7982-4413
Current Organisations
KU Leuven
,
University of Queensland
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
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.
Structural properties of condensed matter | Condensed matter physics | Molecular and organic electronics | Photonics optoelectronics and optical communications |
Publisher: AIP Publishing
Date: 21-11-2013
DOI: 10.1063/1.4831947
Abstract: We report room-temperature Raman studies of strained (100) and (311)B GaAs1−xBix epitaxial layers for x ≤ 0.039. The Raman spectra exhibit a two-mode behavior, as well as disorder-activated GaAs-like phonons. The experimental results show that the GaAs-like LO(Γ) mode experiences a strong composition-dependent redshift as a result of alloying. The peak frequency decreases linearly from the value for pure GaAs (∼293 cm−1) with the alloyed Bi fraction x and the introduced in-plane lattice strain ε∥, by ΔωLO=Δωalloy−Δωstrain. X-ray diffraction measurements are used to determine x and ε∥ allowing Δωalloy to be decoupled and is estimated to be −12(±4) cm−1/x for (100) GaAs1−xBix. ΔωLO is measured to be roughly double for s les grown on (311)B-oriented substrates to that of (100) GaAs. This large difference in redshift is accounted for by examining the Bi induced strain, effects from alloying, and defects formed during high-index (311)B crystal growth.
Publisher: American Chemical Society (ACS)
Date: 17-06-2021
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D2NR06427H
Abstract: MACl post-treatment of MAPbI 3 nanoparticles in a mixed solvent successfully suppresses surface traps, associated with an improved PL intensity and lifetime, brighter and longer ON-states in PL blinking, and a more stable, enhanced photocurrent.
Publisher: Elsevier BV
Date: 12-2021
Publisher: The Optical Society
Date: 18-09-2014
DOI: 10.1364/OME.4.002133
Publisher: Elsevier BV
Date: 02-2021
Publisher: American Chemical Society (ACS)
Date: 09-2017
DOI: 10.1021/ACS.ACCOUNTS.7B00295
Abstract: Interest for functional silver clusters (Ag-CLs) has rapidly grown over years due to large advances in the field of nanoscale fabrication and materials science. The continuous development of strategies to fabricate small-scale silver clusters, together with their interesting physicochemical properties (molecule-like discrete energy levels, for ex le), make them very attractive for a wide variety of applied research fields, from biotechnology and the environmental sciences to fundamental chemistry and physics. Apart from useful catalytic properties, silver clusters (Ag
Publisher: Wiley
Date: 26-02-2021
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/C9MH00500E
Abstract: The recent surge of scientific interest for lead halide perovskite semiconductors and optoelectronic devices has seen a mix of materials science sub-fields converge on the same “magical” crystal structure.
Publisher: Wiley
Date: 31-08-2020
Publisher: American Chemical Society (ACS)
Date: 17-06-2021
Publisher: American Association for the Advancement of Science (AAAS)
Date: 16-08-2019
Abstract: The perovskite materials used for solar cells and light-emitting diodes (which are black in color) are generally less stable at room temperature than the electronically inactive nonperovskite phases (which are yellow in color). Steele et al. show that for CsPbI 3 , strain induced in a thin film after annealing the material to 330°C and then rapidly cooling it to room temperature kinetically trapped the black phase. Grazing-incidence wide-angle x-ray scattering revealed the crystal distortions and texture formation created by interfacial strain. Science , this issue p. 679
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9NA00188C
Abstract: Carbon black is chemically activated by selective TiO 2 photocatalytic oxidation functionalizing the graphitic carbon fraction, while mineralizing amorphous carbon.
Publisher: American Chemical Society (ACS)
Date: 13-08-2019
Publisher: Wiley
Date: 11-06-2023
Abstract: The frequency of reports utilizing synchrotron‐based grazing incident wide angle X‐ray scattering (GIWAXS) to study metal halide perovskite thin films has exploded recently, as this technique has proven invaluable for understanding several structure‐property relationships that fundamentally limit optoelectronic performance. The GIWAXS geometry and temporal resolution are also inherently compatible with in situ and operando setups (including ISOS protocols), and a relatively large halide perovskite research community has deployed GIWAXS to unravel important kinetic and dynamic features in these materials. Considering its rising popularity, the aim here is to accelerate the required learning curve for new experimentalists by clearly detailing the underlying analytical concepts which can be leveraged to maximize GIWAXS studies of polycrystalline thin films and devices. Motivated by the vast range of measurement conditions offered, together with the wide variety of compositions and structural motifs available (i.e., from single‐crystal and polycrystalline systems, to quantum dots and layered superlatices), a comprehensive framework for conducting effective GIWAXS experiments is outlined for different purposes. It is anticipated that providing a clear perspective for this topic will help elevate the quality of future GIWAXS studies—which have become routine—and provide the impetus required to develop novel GIWAXS approaches to resolve unsettled scientific questions.
Publisher: Springer Science and Business Media LLC
Date: 06-12-2022
DOI: 10.1038/S41467-022-35255-9
Abstract: The black perovskite phase of CsPbI 3 is promising for optoelectronic applications however, it is unstable under ambient conditions, transforming within minutes into an optically inactive yellow phase, a fact that has so far prevented its widespread adoption. Here we use coarse photolithography to embed a PbI 2 -based interfacial microstructure into otherwise-unstable CsPbI 3 perovskite thin films and devices. Films fitted with a tessellating microgrid are rendered resistant to moisture-triggered decay and exhibit enhanced long-term stability of the black phase (beyond 2.5 years in a dry environment), due to increasing the phase transition energy barrier and limiting the spread of potential yellow phase formation to structurally isolated domains of the grid. This stabilizing effect is readily achieved at the device level, where unencapsulated CsPbI 3 perovskite photodetectors display ambient-stable operation. These findings provide insights into the nature of phase destabilization in emerging CsPbI 3 perovskite devices and demonstrate an effective stabilization procedure which is entirely orthogonal to existing approaches.
Publisher: American Chemical Society (ACS)
Date: 11-07-2017
Publisher: Wiley
Date: 29-04-2019
Abstract: The extraordinary properties of lead‐halide perovskite materials have spurred intense research, as they have a realistic perspective to play an important role in future photovoltaic devices. It is known that these materials undergo a number of structural phase transitions as a function of temperature that markedly alter their optical and electronic properties. The precise phase transition temperature and exact crystal structure in each phase, however, are controversially discussed in the literature. The linear thermal expansion of single crystals of APbX 3 (A = methylammonium (MA), formamidinium (FA) X = I, Br) below room temperature is measured using a high‐resolution capacitive dilatometer to determine the phase transition temperatures. For δ‐FAPbI 3 , two wide regions of negative thermal expansion below 173 and 54 K, and a cascade of sharp transitions for FAPbBr 3 that have not previously been reported are uncovered. Their respective crystal phases are identified via powder X‐ray diffraction. Moreover, it is demonstrated that transport under steady‐state illumination is considerably altered at the structural phase transition in the MA compounds. The results provide advanced insights into the evolution of the crystal structure with decreasing temperature that are essential to interpret the growing interest in investigating the electronic, optical, and photonic properties of lead‐halide perovskite materials.
Publisher: American Chemical Society (ACS)
Date: 07-2021
DOI: 10.1021/JACS.1C05046
Publisher: IOP Publishing
Date: 22-06-2015
Publisher: American Chemical Society (ACS)
Date: 22-08-2017
Abstract: Metal-organic frameworks (MOFs) are investigated for the adsorption of aromatic amino acids l-phenylalanine (l-Phe), l-tryptophan (l-Trp), and l-tyrosine (l-Tyr) from aqueous solutions. After screening a range of water-stable MOFs, the hydrophobic Zr-MOF MIL-140C emerged as the best performing material, exhibiting uptakes of 15 wt % for l-Trp and 20 wt % for l-Phe. These uptakes are 5-10 wt % higher than those of large-pore zeolites Beta and Y. Both single-compound and competitive adsorption isotherms for l-Phe and l-Trp were experimentally obtained at the natural pH of these amino acid mixtures (pH 6.5-7) without additional pH modification. We find that the hydrophobic nature of MIL-140C and the capacity of l-Trp to form hydrogen bonds favor the uptake of l-Trp with its larger indole moiety compared to the smaller phenyl side group of l-Phe. On the basis of literature and vibrational analysis, observations of hydrogen-bonded l-Trp within the MIL-140C framework are evidenced by red- and blue-shifted -NH vibrations (3400 cm
Publisher: Wiley
Date: 16-10-2021
Abstract: Metal halide perovskites draw increasing attention as photodetector materials due to their strong visible light absorption and resulting photocurrent. The development of efficient fabrication routes to realize high‐resolution perovskite pixel arrays is critical to enable practical devices. Herein, a dry lift‐off process to fabricate methylammonium lead iodide (MAPbI 3 ) pixels on different substrates is reported, with a resolution down to 5 μm. Accordingly, 8 × 10 photodetector arrays are fabricated on both glass and flexible polyethylene terephthalate (PET). These arrays show a sensitive photoresponse over a broad wavelength range from 320 to 760 nm. Moreover, when encapsulated by a Parylene‐C overlayer, the photodetector arrays on glass substrate show remarkable air stability, without noticeable performance loss after 10 days in ambient air, and the flexible photodetector arrays on PET substrate show excellent bending tolerance, retaining nearly 95% of the response after 170 bending cycles.
Publisher: American Chemical Society (ACS)
Date: 26-03-2021
Publisher: American Chemical Society (ACS)
Date: 02-2021
Publisher: American Association for the Advancement of Science (AAAS)
Date: 10-01-2020
Abstract: Li-ion conductivity increases with introduction of an interfacial ice layer in nano-SCE.
Publisher: Elsevier BV
Date: 03-2019
DOI: 10.1016/J.JCIS.2018.11.010
Abstract: Layered double hydroxides (LDH) have been proposed for phosphate (PO
Publisher: American Chemical Society (ACS)
Date: 31-12-2019
Publisher: Elsevier BV
Date: 02-2022
Publisher: Elsevier BV
Date: 08-2018
DOI: 10.1016/J.PBIOMOLBIO.2018.03.004
Abstract: We review the salient evidence consistent with or predicted by the Hoyle-Wickramasinghe (H-W) thesis of Cometary (Cosmic) Biology. Much of this physical and biological evidence is multifactorial. One particular focus are the recent studies which date the emergence of the complex retroviruses of vertebrate lines at or just before the Cambrian Explosion of ∼500 Ma. Such viruses are known to be plausibly associated with major evolutionary genomic processes. We believe this coincidence is not fortuitous but is consistent with a key prediction of H-W theory whereby major extinction- ersification evolutionary boundaries coincide with virus-bearing cometary-bolide bombardment events. A second focus is the remarkable evolution of intelligent complexity (Cephalopods) culminating in the emergence of the Octopus. A third focus concerns the micro-organism fossil evidence contained within meteorites as well as the detection in the upper atmosphere of apparent incoming life-bearing particles from space. In our view the totality of the multifactorial data and critical analyses assembled by Fred Hoyle, Chandra Wickramasinghe and their many colleagues since the 1960s leads to a very plausible conclusion - life may have been seeded here on Earth by life-bearing comets as soon as conditions on Earth allowed it to flourish (about or just before 4.1 Billion years ago) and living organisms such as space-resistant and space-hardy bacteria, viruses, more complex eukaryotic cells, fertilised ova and seeds have been continuously delivered ever since to Earth so being one important driver of further terrestrial evolution which has resulted in considerable genetic ersity and which has led to the emergence of mankind.
Publisher: Wiley
Date: 24-04-2021
Abstract: Research into organic–inorganic lead halide perovskites as photoactive material in solar cells and other electro‐optical devices has made immense progress in recent years. However, efficiency losses resulting from deep traps associated with framework defects, still limit the performance of perovskite semiconductors. Defect passivation by the incorporation of dopants, such as chloride doping in methylammonium lead iodide (MAPbI 3 ) perovskite, is stated as one of the most efficient ways to reduce trap densities. Commonly used parameters like improved photoluminescence (PL) quantum yields and extended PL lifetimes provide nonconclusive experimental evidence on trap density suppression by chloride doping. In this work, the effect of chloride doping on the crystal morphology, composition, and PL of MAPbI 3 nanocrystals is carefully investigated. Besides the anticipated enhanced PL intensity and extended PL lifetime, single‐particle PL intermittency studies reveal brighter and longer ON‐states with increasing amounts of chloride doping, which represents additional evidence of effective chloride‐induced trap passivation. These findings provide important guidelines for generating lead halide perovskite materials with significantly reduced trap densities toward the fabrication of high‐performance optoelectronic devices.
Publisher: Elsevier BV
Date: 07-2021
Publisher: American Chemical Society (ACS)
Date: 28-12-2021
Publisher: American Chemical Society (ACS)
Date: 09-11-2021
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2CC02453E
Abstract: Development of metal halide perovskite photocatalysts that can efficiently perform selective organic oxidations in combination with H 2 evolution at mild conditions.
Publisher: American Chemical Society (ACS)
Date: 05-12-2018
Publisher: Wiley
Date: 20-06-2019
DOI: 10.1002/POLA.29424
Publisher: AIP Publishing
Date: 08-2016
DOI: 10.1063/1.4959824
Abstract: Due to their interesting orientation-dependent properties, the ability to grow high-index semiconductor crystals and nanostructures extends the design palette for applications based on these materials. Notably, a source containing a systematic reporting of what the Raman tensors are for an arbitrary high-index zincblende material is yet to appear in the literature. Herein, we present the polarized Raman backscattering selection rules for arbitrary (hhl)-oriented diamond- and zincblende-type crystal surfaces and verify their correctness through experiment (up to (115)). Considering the many degrees of freedom available to common polarized micro-Raman scattering instruments, and the unique local orientation of the probed material, we further examine a range of consequences imposed by the selection rules for the Raman backscattering method.
Publisher: Wiley
Date: 03-06-2020
Publisher: American Chemical Society (ACS)
Date: 27-12-2021
DOI: 10.1021/ACS.JPCLETT.1C03668
Abstract: Sunlight is an abundant and clean energy source, the harvesting of which could make a significant contribution to society's increasing energy demands. Metal halide perovskites (MHP) have recently received attention for solar fuel generation through photocatalysis and solar-driven electrocatalysis. However, MHP photocatalysis is limited by low solar energy conversion efficiency, poor stability, and impractical reaction conditions. Compared to photocatalysis, MHP solar-driven electrocatalysis not only exhibits higher solar conversion efficiency but also is more stable when operating under practical reaction conditions. In this Perspective, we outline three leading types of MHP solar-driven electrocatalysis device technologies now in the research spotlight, namely, (1) photovoltaic-electrochemical (PV-EC), (2) photovoltaic-photoelectrochemical (PV-PEC), and (3) photoelectrochemical (PEC) approaches for solar-to-fuel reactions, including water-splitting and the CO
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5NR06676J
Abstract: In this study we report in-plane nanotracks produced by molecular-beam-epitaxy (MBE) exhibiting lateral self-assembly and unusual periodic and out-of-phase height variations across their growth axes.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5RA23621E
Abstract: We present a low-cost fabrication procedure for the production of nanoscale periodic GaAs nanopillar arrays, using the nanosphere lithography technique as a templating mechanism and the electrochemical metal assisted etch process (MacEtch).
Publisher: American Chemical Society (ACS)
Date: 04-08-2017
Publisher: American Chemical Society (ACS)
Date: 22-05-2017
Abstract: Superconductivity and ferromagnetism are two mutually antagonistic states in condensed matter. Research on the interplay between these two competing orderings sheds light not only on the cause of various quantum phenomena in strongly correlated systems but also on the general mechanism of superconductivity. Here we report on the observation of the electronic entanglement between superconducting and ferromagnetic states in hydrogenated boron-doped nanodiamond films, which have a superconducting transition temperature T
Publisher: IEEE
Date: 09-2013
Publisher: SPIE
Date: 22-05-2018
DOI: 10.1117/12.2316568
Publisher: Wiley
Date: 16-06-2021
Abstract: The study of luminescent silver nanoclusters confined inside porous zeolite crystal has garnered the interest of fundamental and applied nanomaterials research owing to the fascinating properties they exhibit once stabilized into small, molecule‐like clusters. Notably, such systems display a tunable optical emission (spanning nearly the entire visible range) and high luminescence quantum yields, features that are both sensitive to external stimuli and changes in the local environment of the cluster. Together, this combination of physical attributes has motivated research based on the intentional introduction of external atomic and molecular species into zeolites’ interior pore volume. In this progress report, recent discoveries which have helped to elucidate the dynamic luminescent emission properties of silver nanoclusters confined in zeolites are examined, highlighting promising efforts being made toward reaching rational design protocols for their functional synthesis. Several encouraging multicomponent systems that have allowed for the flexible regulation of the luminescence properties of the confined silver nanoclusters are brought into focus. Further, a brief up‐to‐date review of their applications is provided, ranging from efficient light‐emitting devices to sensitive (bio)sensors.
Publisher: American Chemical Society (ACS)
Date: 06-04-2022
Abstract: The development of improved catalysts capable of performing the Suzuki coupling reaction has attracted considerable attention. Recent findings have shown that the use of photoactive catalysts improves the performance, while the reaction mechanism and temperature-dependent performance of such systems are still under debate. Herein, we report Pd nanocubes/CsPbBr
Publisher: Springer Science and Business Media LLC
Date: 10-08-2021
DOI: 10.1038/S41467-021-25092-7
Abstract: Molecular additives are widely utilized to minimize non-radiative recombination in metal halide perovskite emitters due to their passivation effects from chemical bonds with ionic defects. However, a general and puzzling observation that can hardly be rationalized by passivation alone is that most of the molecular additives enabling high-efficiency perovskite light-emitting diodes (PeLEDs) are chelating (multidentate) molecules, while their respective monodentate counterparts receive limited attention. Here, we reveal the largely ignored yet critical role of the chelate effect on governing crystallization dynamics of perovskite emitters and mitigating trap-mediated non-radiative losses. Specifically, we discover that the chelate effect enhances lead-additive coordination affinity, enabling the formation of thermodynamically stable intermediate phases and inhibiting halide coordination-driven perovskite nucleation. The retarded perovskite nucleation and crystal growth are key to high crystal quality and thus efficient electroluminescence. Our work elucidates the full effects of molecular additives on PeLEDs by uncovering the chelate effect as an important feature within perovskite crystallization. As such, we open new prospects for the rationalized screening of highly effective molecular additives.
Publisher: MDPI AG
Date: 17-04-2019
Abstract: Polynorbornenes are already used in a wide range of applications. They are also considered materials for polymer gas separation membranes because of their favorable thermal and chemical resistance, rigid backbone and varied chemistry. In this study, the use of 5-vinyl-2-norbornene (VNB), a new monomer in the field of gas separations, is investigated by synthesizing two series of polymers via a vinyl-addition polymerization. The first series investigates the influence of the VNB content on gas separation in a series of homo and copolymers with norbornene. The second series explores the influence of the crosslinking of polyvinylnorbornene (pVNB) on gas separation. The results indicate that while crosslinking had little effect, the gas separation performance could be fine-tuned by controlling the VNB content. As such, this work demonstrates an interesting way to significantly extend the fine-tuning possibilities of polynorbornenes for gas separations.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 07-07-2023
Abstract: Silicon solar cells are approaching their theoretical efficiency limit of 29%. This limitation can be exceeded with advanced device architectures, where two or more solar cells are stacked to improve the harvesting of solar energy. In this work, we devise a tandem device with a perovskite layer conformally coated on a silicon bottom cell featuring micrometric pyramids—the industry standard—to improve its photocurrent. Using an additive in the processing sequence, we regulate the perovskite crystallization process and alleviate recombination losses occurring at the perovskite top surface interfacing the electron-selective contact [buckminsterfullerene (C 60 )]. We demonstrate a device with an active area of 1.17 square centimeters, reaching a certified power conversion efficiency of 31.25%.
Publisher: American Chemical Society (ACS)
Date: 26-02-2018
Publisher: American Chemical Society (ACS)
Date: 22-03-2018
DOI: 10.1021/ACS.JPCLETT.8B00399
Abstract: The direct synthesis of hierarchically intergrown silicalite-1 can be achieved using a specific diquaternary ammonium agent. However, the location of these molecules in the zeolite framework, which is critical to understand the formation of the material, remains unclear. Where traditional characterization tools have previously failed, herein we use polarized stimulated Raman scattering (SRS) microscopy to resolve molecular organization inside few-micron-sized crystals. Through a combination of experiment and first-principles calculations, our investigation reveals the preferential location of the templating agent inside the linear pores of the MFI framework. Besides illustrating the attractiveness of SRS microscopy in the field of material science to study and spatially resolve local molecular distribution as well as orientation, these results can be exploited in the design of new templating agents for the preparation of hierarchical zeolites.
Publisher: Research Square Platform LLC
Date: 25-09-2023
Publisher: The Optical Society
Date: 22-12-2014
DOI: 10.1364/OE.22.032261
Publisher: IOP Publishing
Date: 05-03-2015
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2TC02498E
Abstract: A new perovskite-based turn-on sensor, Cs 4 PbBr 6 /FAU-Y, is designed by depositing the precursor of CsPbBr 3 on hygroscopic zeolite FAU-Y. This sensor shows an excellent fluorescence response when exposed to both low and high humidity conditions.
Publisher: American Chemical Society (ACS)
Date: 07-08-2018
Abstract: The room-temperature charge carrier mobility and excitation-emission properties of metal halide perovskites are governed by their electronic band structures and intrinsic lattice phonon scattering mechanisms. Establishing how charge carriers interact within this scenario will have far-reaching consequences for developing high-efficiency materials for optoelectronic applications. Herein we evaluate the charge carrier scattering properties and conduction band environment of the double perovskite Cs
Publisher: Wiley
Date: 17-09-2018
Abstract: The sensitive detection of X-rays embodies an important research area, being motivated by a common desire to minimize the radiation doses required for detection. Among metal halide perovskites, the double-perovskite Cs
Publisher: American Chemical Society (ACS)
Date: 29-09-2017
Publisher: American Chemical Society (ACS)
Date: 14-09-2020
Publisher: The Optical Society
Date: 07-05-2014
DOI: 10.1364/OE.22.011680
Publisher: American Chemical Society (ACS)
Date: 20-01-2021
Publisher: Springer Science and Business Media LLC
Date: 29-01-2019
DOI: 10.1038/S41467-019-08326-7
Abstract: Halide perovskites possess enormous potential for various optoelectronic applications. Presently, a clear understanding of the interplay between the lattice and electronic effects is still elusive. Specifically, the weakly absorbing tail states and dual emission from perovskites are not satisfactorily described by existing theories based on the Urbach tail and reabsorption effect. Herein, through temperature-dependent and time-resolved spectroscopy on metal halide perovskite single crystals with organic or inorganic A-site cations, we confirm the existence of indirect tail states below the direct transition edge to arise from a dynamical Rashba splitting effect, caused by the PbBr 6 octahedral thermal polar distortions at elevated temperatures. This dynamic effect is distinct from the static Rashba splitting effect, caused by non-spherical A-site cations or surface induced lattice distortions. Our findings shed fresh perspectives on the electronic-lattice relations paramount for the design and optimization of emergent perovskites, revealing broad implications for light harvesting hoto-detection and light emission/lasing applications.
Publisher: AIP Publishing
Date: 04-2023
DOI: 10.1063/5.0144344
Abstract: Metal-halide perovskites (MHPs) exhibit excellent properties for application in optoelectronic devices. The bottleneck for their incorporation is the lack of long-term stability such as degradation due to external conditions (heat, light, oxygen, moisture, and mechanical stress), but the occurrence of phase transitions also affects their performance. Structural phase transitions are often influenced by phonon modes. Hence, an insight into both the structure and lattice dynamics is vital to assess the potential of MHPs. In this study, GIWAXS and Raman spectroscopy are applied, supported by density functional theory calculations, to investigate the apparent manifestation of structural phase transitions in the MHP CsPbBr3. Macroscopically, CsPbBr3 undergoes phase transitions between a cubic (α), tetragonal (β), and orthorhombic (γ) phase with decreasing temperature. However, microscopically, it has been argued that only the γ phase exists, while the other phases exist as averages over length and time scales within distinct temperature ranges. Here, direct proof is provided for this conjecture by analyzing both theoretical diffraction patterns and the evolution of the tilting angle of the PbBr6 octahedra from molecular dynamics simulations. Moreover, sound agreement between experimental and theoretical Raman spectra allowed to identify the Raman active phonon modes and to investigate their frequency as a function of temperature. As such, this work increases the understanding of the structure and lattice dynamics of CsPbBr3 and similar MHPs.
Publisher: American Chemical Society (ACS)
Date: 19-08-2019
Publisher: Springer Science and Business Media LLC
Date: 25-02-2021
Publisher: American Chemical Society (ACS)
Date: 21-08-2018
DOI: 10.1021/ACS.JPCLETT.8B01890
Abstract: The appealing luminescent properties of Ag-zeolites have been shown to be dependent on the local environment of the confined silver clusters. Herein, we shed light on the properties of Ag clusters inside hydrated Linde-type A (LTA) zeolites and relate them to the nature of the host framework when expanded and compressed by the incorporation of Li
Publisher: American Chemical Society (ACS)
Date: 23-06-2020
Abstract: Metal halide perovskites with direct band gap and strong light absorption are promising materials for harvesting solar energy however, their relatively narrow band gap limits their redox ability when used as a photocatalyst. Adding a second semiconductor component with the appropriate band structure offsets can generate a Z-scheme photocatalytic system, taking full advantage of the perovskite's intrinsic properties. In this work, we develop a direct Z-scheme photocatalyst based on formamidinium lead bromide and bismuth tungstate (FAPbBr
Publisher: Springer Science and Business Media LLC
Date: 05-07-2016
DOI: 10.1038/SREP28860
Abstract: Herein we investigate a (001)-oriented GaAs 1− x Bi x /GaAs structure possessing Bi surface droplets capable of catalysing the formation of nanostructures during Bi-rich growth, through the vapour-liquid-solid mechanism. Specifically, self-aligned “nanotracks” are found to exist trailing the Bi droplets on the s le surface. Through cross-sectional high-resolution transmission electron microscopy the nanotracks are revealed to in fact be elevated above surface by the formation of a subsurface planar nanowire, a structure initiated mid-way through the molecular-beam-epitaxy growth and embedded into the epilayer, via epitaxial overgrowth. Electron microscopy studies also yield the morphological, structural and chemical properties of the nanostructures. Through a combination of Bi determination methods the compositional profile of the film is shown to be graded and inhomogeneous. Furthermore, the coherent and pure zincblende phase property of the film is detailed. Optical characterisation of features on the s le surface is carried out using polarised micro-Raman and micro-photoluminescence spectroscopies. The important light producing properties of the surface nanostructures are investigated through pump intensity-dependent micro-PL measurements, whereby relatively large local inhomogeneities are revealed to exist on the epitaxial surface for important optical parameters. We conclude that such surface effects must be considered when designing and fabricating optical devices based on GaAsBi alloys.
Publisher: American Chemical Society (ACS)
Date: 22-09-2022
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9TC04674G
Abstract: The applicability of Ag-exchanged zeolites as efficient phosphors for the development of near ultra-violet primary LEDs is described.
Publisher: Wiley
Date: 19-02-2019
Publisher: eSAT Publishing House
Date: 25-09-2013
Publisher: American Chemical Society (ACS)
Date: 06-03-2020
Start Date: 05-2023
End Date: 05-2026
Amount: $426,062.00
Funder: Australian Research Council
View Funded Activity