ORCID Profile
0000-0002-0100-480X
Current Organisation
University of Newcastle Australia
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Publisher: Informa UK Limited
Date: 14-03-2022
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: Wiley
Date: 03-05-2021
Abstract: Organic–inorganic mixed halide perovskites have emerged as an excellent class of materials with a unique combination of optoelectronic properties, suitable for a plethora of applications ranging from solar cells to light‐emitting diodes and photoelectrochemical devices. Recent works have showcased hybrid perovskites for electronic applications through improvements in materials design, processing, and device stability. Herein, a comprehensive up‐to‐date review is presented on hybrid perovskite electronics with a focus on transistors and memories. These applications are supported by the fundamental material properties of hybrid perovskite semiconductors such as tunable bandgap, ambipolar charge transport, reasonable mobility, defect characteristics, and solution processability, which are highlighted first. Then, recent progresses on perovskite‐based transistors are reviewed, covering aspects of fabrication process, patterning techniques, contact engineering, 2D versus 3D material selection, and device performance. Furthermore, applications of perovskites in nonvolatile memories and artificial synaptic devices are presented. The ambient instability of hybrid perovskites and the strategies to tackle this bottleneck are also discussed. Finally, an outlook and opportunities to develop perovskite‐based electronics as a competitive and feasible technology are highlighted.
Publisher: Wiley
Date: 05-01-2022
Abstract: Integrating multiple semiconductors with distinct physical properties is a practical design strategy for realizing novel optoelectronic devices with unprecedented functionalities. In this work, a photonic resistive switching (RS) memory is demonstrated based on solution‐processed bilayers of strontium titanate (SrTiO 3 or STO) quantum dots (QDs) and all‐inorganic halide perovskite CsPbBr 3 (CPB) with an Ag/STO/CPB/Au architecture. Compared with the single‐layer STO or CPB RS device, the double‐layer device shows considerably improved RS performance with a high switching ratio over 10 5 , an endurance of 3000 cycles, and a retention time longer than 2 × 10 4 s. The formation of heterojunction between STO and CPB significantly enhances the high resistance state, and the separation of the active silver electrode and the CPB layer contributes to the long‐term stability. More importantly, the photonic RS device exhibits UV–visible dual‐band response due to the photogating effect and the light‐induced modification of the heterojunction barrier. Last, tri‐mode operation, i.e., photodetector, memory, and photomemory, is demonstrated via tailoring the light and electric stimuli. This bilayer device architecture provides a unique approach toward enhancing the performance of photoresponsive data‐storage devices.
Publisher: Elsevier BV
Date: 10-2019
Publisher: American Chemical Society (ACS)
Date: 19-08-2020
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: Wiley
Date: 02-06-2020
Publisher: Wiley
Date: 03-07-2018
Publisher: American Chemical Society (ACS)
Date: 28-07-2020
Publisher: Wiley
Date: 21-08-2022
Abstract: Metal‐halide perovskites have drawn profuse attention during the past decade, owing to their excellent electrical and optical properties, facile synthesis, efficient energy conversion, and so on. Meanwhile, the development of information storage technologies and digital communications has fueled the demand for novel semiconductor materials. Low‐dimensional perovskites have offered a new force to propel the developments of the memory field due to the excellent physical and electrical properties associated with the reduced dimensionality. In this review, the mechanisms, properties, as well as stability and performance of low‐dimensional perovskite memories, involving both molecular‐level perovskites and structure‐level nanostructures, are comprehensively reviewed. The property–performance correlation is discussed in‐depth, aiming to present effective strategies for designing memory devices based on this new class of high‐performance materials. Finally, the existing challenges and future opportunities are presented.
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8CP03945C
Abstract: We review emerging low-cost solution-processed resistive random-access memory (ReRAM) made of either hybrid nanocomposites or hybrid organo-lead halide perovskites.
Publisher: Elsevier BV
Date: 07-2020
Publisher: Wiley
Date: 19-02-2020
Publisher: Wiley
Date: 27-09-2018
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3TA00318C
Abstract: Novel structured thiadiazole-attached carbon nitrides are first synthesized via sintering 5-amino-1,3,4-thiadiazole-2-thiol, demonstrating excellent performances towards photocatalytic H 2 evolution under visible light irradiation.
Publisher: Wiley
Date: 04-12-2021
Abstract: The extraordinary electronic, optical, and mechanical characteristics of 2D materials make them promising candidates for optoelectronics, specifically in infrared (IR) detectors owing to their flexible composition and tunable optoelectronic properties. This review presents the recent progress in IR detectors composed of 2D materials and their hybrid structures, including graphene, black phosphorous, transition metal dichalcogenides, halide perovskite as well as other new layered materials and their heterostructures. The focus is on the short‐wave, mid‐wave, and long‐wave infrared regimes, which pose a grand challenge for rational materials and device designs. The dependence of the device performance on the optical and electronic properties of 2D materials is extensively discussed, aiming to present the general strategies for designing optoelectronic devices with optimal performance. Furthermore, the recent results on 2D material‐based heterostructures are presented with an emphasis on the relationship between band alignment, charge transfer, and IR photodetection. Finally, a summary is given as well as the discussion of existing challenges and future directions.
Publisher: American Chemical Society (ACS)
Date: 04-2021
Publisher: Wiley
Date: 17-04-2021
Publisher: Wiley
Date: 25-01-2023
Abstract: Solar‐driven photothermal water evaporation is considered an elegant and sustainable technology for freshwater production. The existing systems, however, often suffer from poor stability and biofouling issues, which severely h er their prospects in practical applications. Conventionally, photothermal materials are deposited on the membrane supports via vacuum‐assisted filtration or dip‐coating methods. Nevertheless, the weak inherent material‐membrane interactions frequently lead to poor durability, and the photothermal material layer can be easily peeled off from the hosting substrates or partially dissolved when immersed in water. In the present article, the discovery of the incorporation of borophene into cellulose nanofibers (CNF), enabling excellent environmental stability with a high light‐to‐heat conversion efficiency of 91.5% and water evaporation rate of 1.45 kg m −2 h −1 under simulated sunlight is reported. It is also demonstrated that borophene papers can be employed as an excellent active photothermal material for eliminating almost 100% of both gram‐positive and gram‐negative bacteria within 20 min under three sun irradiations. The result opens a new direction for the design of borophene‐based papers with unique photothermal properties which can be used for the effective treatment of a wide range of wastewaters.
Publisher: American Chemical Society (ACS)
Date: 27-10-2022
Publisher: American Chemical Society (ACS)
Date: 09-07-2020
Publisher: American Chemical Society (ACS)
Date: 08-11-2018
Abstract: The direction of ferroelectric polarization is prescribed by the symmetry of the crystal structure. Therefore, rotation of the polarization direction is largely limited, despite the opportunity it offers in understanding important dielectric phenomena such as piezoelectric response near the morphotropic phase boundaries and practical applications such as ferroelectric memory. In this study, we report the observation of continuous rotation of ferroelectric polarization in order-disorder-type LiNbO
Publisher: American Chemical Society (ACS)
Date: 03-04-2020
Publisher: American Chemical Society (ACS)
Date: 18-09-2020
Publisher: Wiley
Date: 09-08-2020
Publisher: Wiley
Date: 24-01-2023
Abstract: Carbon‐based quantum dots (QDs) have emerged as a fascinating class of advanced materials with a unique combination of optoelectronic, biocompatible, and catalytic characteristics, apt for a plethora of applications ranging from electronic to photoelectrochemical devices. Recent research works have established carbon‐based QDs for those frontline applications through improvements in materials design, processing, and device stability. This review broadly presents the recent progress in the synthesis of carbon‐based QDs, including carbon QDs, graphene QDs, graphitic carbon nitride QDs and their heterostructures, as well as their salient applications. The synthesis methods of carbon‐based QDs are first introduced, followed by an extensive discussion of the dependence of the device performance on the intrinsic properties and nanostructures of carbon‐based QDs, aiming to present the general strategies for device designing with optimal performance. Furthermore, erse applications of carbon‐based QDs are presented, with an emphasis on the relationship between band alignment, charge transfer, and performance improvement. Among the applications discussed in this review, much focus is given to photo and electrocatalytic, energy storage and conversion, and bioapplications, which pose a grand challenge for rational materials and device designs. Finally, a summary is presented, and existing challenges and future directions are elaborated.
Publisher: Elsevier BV
Date: 10-2023
Publisher: Optica Publishing Group
Date: 30-10-2020
DOI: 10.1364/PRJ.402411
Abstract: Halide perovskites, such as methylammonium lead halide perovskites ( MAPbX 3 , X = I , Br, and Cl), are emerging as promising candidates for a wide range of optoelectronic applications, including solar cells, light-emitting diodes, and photodetectors, due to their superior optoelectronic properties. All-inorganic lead halide perovskites CsPbX 3 are attracting a lot of attention because replacing the organic cations with Cs + enhances the stability, and its halide-mixing derivatives offer broad bandgap tunability covering nearly the entire visible spectrum. However, there is evidence suggesting that the optical properties of mixed-halide perovskites are influenced by phase segregation under external stimuli, especially illumination, which may negatively impact the performance of optoelectronic devices. It is reported that the mixed-halide perovskites in forms of thin films and nanocrystals are segregated into a low-bandgap I-rich phase and a high-bandgap Br-rich phase. Herein, we present a critical review on the synthesis and basic properties of all-inorganic perovskites, phase-segregation phenomena, plausible mechanisms, and methods to mitigate phase segregation, providing insights on advancing mixed-halide perovskite optoelectronics with reliable performance.
Publisher: Springer Science and Business Media LLC
Date: 11-05-2022
DOI: 10.1038/S41586-022-04588-2
Abstract: The scaling of silicon metal-oxide-semiconductor field-effect transistors has followed Moore's law for decades, but the physical thinning of silicon at sub-ten-nanometre technology nodes introduces issues such as leakage currents
Publisher: Wiley
Date: 16-08-2019
Publisher: Wiley
Date: 10-07-2017
Publisher: Wiley
Date: 11-03-2022
Abstract: Contact engineering is a prerequisite for achieving desirable functionality and performance of semiconductor electronics, which is particularly critical for organic–inorganic hybrid halide perovskites due to their ionic nature and highly reactive interfaces. Although the interfaces between perovskites and charge‐transporting layers have attracted lots of attention due to the photovoltaic and light‐emitting diode applications, achieving reliable perovskite/electrode contacts for electronic devices, such as transistors and memories, remains as a bottleneck. Herein, a critical review on the elusive nature of perovskite/electrode interfaces with a focus on the interfacial electrochemistry effects is presented. The basic guidelines of electrode selection are given for establishing non‐polarized interfaces and optimal energy level alignment for perovskite materials. Furthermore, state‐of‐the‐art strategies on interface‐related electrode engineering are reviewed and discussed, which aim at achieving ohmic transport and eliminating hysteresis in perovskite devices. The role and multiple functionalities of self‐assembled monolayers that offer a unique approach toward improving perovskite/electrode contacts are also discussed. The insights on electrode engineering pave the way to advancing stable and reliable perovskite devices in erse electronic applications.
Publisher: American Chemical Society (ACS)
Date: 06-12-2021
Publisher: AIP Publishing
Date: 15-07-2020
DOI: 10.1063/5.0009713
Abstract: Artificial iconic memories, also called photomemories, are new types of nonvolatile memory that can simultaneously detect and store light information in a monolithic device. Several approaches have been proposed to construct artificial iconic memories, such as three-terminal field effect transistors, which can achieve an effective control of the gate voltage and external light terminals. The drawbacks in constructing these memories involve complicated fabrication processes, and the resulting performance of, for ex le, perovskite transistor-type photomemories is limited by the low carrier mobilities and poor ambient stabilities, whereas architectures based on floating gate modulations entail strict interface engineering and poor device reliability. In this paper, we propose a novel monolithic artificial iconic memory with a multilayer architecture of indium tin oxide erovskite/gold erovskite/silver, which combines the memory and photodetector functionalities of perovskites in an integrated device. The bottom perovskite layer plays the role of a photodetector, modulating the voltage bias on the top perovskite layer that serves as a resistive switching memory. This multilayer perovskite device can store photo-sensing data in its resistive states, with a memory retention of 5 × 103 s and ambient stability longer than sixty days. As a prototype demonstration, a 7 × 7 artificial iconic memory array is constructed to detect and store data on light intensity distribution, enabling a nonvolatile imaging functionality. Our work provides a new platform for designing perovskite-based architectures with simultaneous light detection and data storage capabilities.
Publisher: Wiley
Date: 23-11-2017
Publisher: Springer Science and Business Media LLC
Date: 27-08-2018
DOI: 10.1038/S41586-018-0451-1
Abstract: The rising demand for radiation detection materials in many applications has led to extensive research on scintillators
Publisher: American Chemical Society (ACS)
Date: 20-12-2020
Abstract: Organolead trihalide perovskites have attracted substantial interest with regard to applications in charge-based photovoltaic and optoelectronic devices because of their low processing costs and remarkable light absorption and charge transport properties. Although spin is an intrinsic quantum descriptor of a particle and spintronics has been a central research theme in condensed matter physics, few studies have explored the spin degree of freedom in the emerging hybrid perovskites. Here, we report the characterization of a spin valve that uses hybrid perovskite films as the spin-transporting medium between two ferromagnetic electrodes. Because of the light-responsive nature of the hybrid perovskite, a high magnetoresistance of 97% and a large spin-diffusion length of 81 nm were achieved at 10 K under light illumination in polycrystalline films. Furthermore, by using thin perovskite single crystals, we discovered that the spin-diffusion length was able to reach 1 μm at low temperatures. Our results indicate that the spin relaxation is not significant as previously expected in such lead-containing materials and demonstrate the potential of low-temperature-processed hybrid perovskites as new active materials in spintronic devices.
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: Wiley
Date: 28-04-2022
Abstract: Hybrid halide perovskites have emerged as highly promising photovoltaic materials because of their exceptional optoelectronic properties, which are often optimized via compositional engineering like mixing halides. It is well established that hybrid perovskites undergo a series of structural phase transitions as temperature varies. In this work, the authors find that phase transitions are substantially suppressed in mixed‐halide hybrid perovskite single crystals of MAPbI 3‐x Br x (MA = CH 3 NH 3 + and x = 1 or 2) using a complementary suite of diffraction and spectroscopic techniques. Furthermore, as a general behavior, multiple crystallographic phases coexist in mixed‐halide perovskites over a wide temperature range, and a slightly distorted monoclinic phase, hitherto unreported for hybrid perovskites, is dominant at temperatures above 100 K. The anomalous structural evolution is correlated with the glassy behavior of organic cations and optical phonons in mixed‐halide perovskites. This work demonstrates the complex interplay between composition engineering and lattice dynamics in hybrid perovskites, shedding new light on their unique properties.
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: American Chemical Society (ACS)
Date: 05-2017
Abstract: Colloidal ZnO nanoparticle (NP) films are recognized as efficient electron transport layers (ETLs) for quantum dot light-emitting diodes (QD-LEDs) with good stability and high efficiency. However, because of the inherently high work function of such films, spontaneous charge transfer occurs at the QD/ZnO interface in such a QD-LED, thus leading to reduced performance. Here, to improve the QD-LED performance, we prepared Ga-doped ZnO NPs with low work functions and tailored band structures via a room-temperature (RT) solution process without the use of bulky organic ligands. We found that the charge transfer at the interface between the CdSe/ZnS QDs and the doped ZnO NPs was significantly weakened because of the incorporated Ga dopants. Remarkably, the as-assembled QD-LEDs, with Ga-doped ZnO NPs as the ETLs, exhibited superior luminances of up to 44 000 cd/m
Publisher: Wiley
Date: 29-04-2020
Publisher: Elsevier BV
Date: 03-2021
Publisher: Wiley
Date: 24-07-2020
Publisher: American Chemical Society (ACS)
Date: 25-04-2019
DOI: 10.1021/ACS.JPCLETT.9B00777
Abstract: To investigate the quantum confinement effect on excitons in hybrid perovskites, single-crystal platelets of CH
Publisher: American Chemical Society (ACS)
Date: 26-02-2021
Publisher: American Chemical Society (ACS)
Date: 17-11-2021
No related grants have been discovered for Xinwei Guan.