A5019127728- Perovskite Materials and Applications
- Conducting polymers and applications
- Organic Electronics and Photovoltaics
- GaN-based semiconductor devices and materials
- Chalcogenide Semiconductor Thin Films
- ZnO doping and properties
- Thin-Film Transistor Technologies
- Semiconductor materials and devices
- Organic Light-Emitting Diodes Research
- Metal and Thin Film Mechanics
- Quantum Dots Synthesis And Properties
- Semiconductor Quantum Structures and Devices
- Ga2O3 and related materials
- Silicon Carbide Semiconductor Technologies
- Magnetic properties of thin films
- Electronic and Structural Properties of Oxides
- Nanowire Synthesis and Applications
- Solid-state spectroscopy and crystallography
- Photonic and Optical Devices
- Ferroelectric and Negative Capacitance Devices
- Fullerene Chemistry and Applications
- Semiconductor materials and interfaces
- Advanced Materials Characterization Techniques
- solar cell performance optimization
- 2D Materials and Applications
University of British Columbia
2021-2024
Hong Kong Baptist University
2014-2021
Kelowna General Hospital
2021
Kowloon Hospital
2017-2020
Hong Kong Polytechnic University
2018
University of Hong Kong
2000-2015
University of Wisconsin–Milwaukee
2005-2012
Pacific Northwest National Laboratory
2007
University of Connecticut
1993-2002
High-quality pinhole-free perovskite film with optimal crystalline morphology is critical for achieving high-efficiency and high-stability solar cells (PSCs). In this study, a p-type π-conjugated polymer poly[(2,6-(4,8-bis(5-(2-ethylhexyl) thiophen-2-yl)-benzo[1,2-b:4,5-b'] dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl) benzo[1',2'-c:4',5'-c'] dithiophene-4,8-dione))] (PBDB-T) introduced into chlorobenzene to form facile effective template-agent during the anti-solvent...
Abstract In this contribution, a facile and universal method is successfully reported to fabricate perovskite solar cells (PSCs) with enhanced efficiency stability. Through dissolving functional conjugated polymers in antisolvent chlorobenzene treat the spinning CH 3 NH PbI film, resultant devices exhibit significantly longevity simultaneously. In‐depth characterizations demonstrate that thin polymer layer well covers top surface of resulting certain passivation morphology modification. More...
A PCDTBT:PC<sub>71</sub>BM solar cell adopted by a ternary strategy with PDTSTPD achieves an overall PCE of 20.8% under indoor illumination.
Carbon-based perovskite solar cells (PVSCs) without hole transport materials are promising for their high stability and low cost, but the electron transporting layer (ETL) of TiO2 is notorious inflicting hysteresis instability. In view its accepting ability, C60 used to replace ETL, forming a so-called all carbon based PVSC. With device structure fluorine-doped tin oxide (FTO)/C60 /methylammonium lead iodide (MAPbI3 )/carbon, power conversion efficiency (PCE) attained up 15.38% hysteresis,...
Abstract Passivation of organometal halide perovskites with polar molecules has been recently demonstrated to improve the photovoltaic device efficiency and stability. However, mechanism is still elusive. Here, it found that both polymers large small dipole moment 3.7 D 0.6 have negligible defect passivation effect on MAPbI 3 perovskite films as evidenced by photothermal deflection spectroscopy. The devices without polymer additives also comparable power conversion efficiencies around 19%....
CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub>-based devices exhibiting a PCE of 12.5% have been achieved by annealing the evaporated precursor multilayers and treating device constituent layers in well controlled atmosphere.
Synthesis of high quality perovskite absorber is a key factor in determining the performance solar cells. We demonstrate that hybrid chemical vapor deposition (HCVD) growth technique can provide level versatility and repeatability to ensure optimal conditions for films as well potential batch processing. It found ambient degree crystallization CH3NH3PbI3 (MAPI) have strong impact on defect density MAPI. HCVD process with slow postdeposition cooling rate significantly reduce shallow deep...
A thick-film (∼200 nm) porphyrin-based P1:PC<sub>71</sub>BM BHJ solar cell achieves an optimized PCE of 18.2%, under a 300 lux illumination 3000 K LED tube.
Tuning the donor–acceptor (D–A) weight ratio is an essential step to optimize performance of a bulk heterojunction (BHJ) solar cell. The unoptimized regime with low acceptor concentration generally unexplored despite it may reveal early stage electronic D–A interactions. In this study, PTB7:PC 71 BM used examine factors that limit device in regime. key limiting factor creation traps and localized states originated from fullerene molecules. Photothermal deflection spectroscopy quantify trap...
The light soaking effect (LSE) is widely known in perovskite solar cells (PVSCs), but its origin still elusive. In this study, we show that common with hysteresis, the LSE owed to ion migration PVSCs. Driven by photovoltage, mobile ions materials (MA+/I–) migrate selective contacts, forming a boosted P-i-N junction resulting enhanced charge separation. Besides, (MA+) can soften and suture PCBM/perovskite interface thus reduce trap density, keeping higher open-circuit voltage. Finally, almost...
Charge transfer (CT) states induced by physisorbed N<sub>2</sub> on ZnO NPs are non-radiative whereas those chemisorbed O<sub>2</sub> radiative.
Record high and hysteresis free perovskite based solar cells are achieved by crystal engineering optimization of carrier transport pathway.
Mobile ions not only have detrimental effects on device performance but also trigger the degradation of perovskite during operation.
Abstract A cryogenic process is introduced to control the crystallization of perovskite layers, eliminating need for use environmentally harmful antisolvents. This enables decoupling nucleation and phases by inhibiting chemical reactions in as‐cast precursor films rapidly cooled down immersion liquid nitrogen. The cooling followed blow‐drying with nitrogen gas, which induces uniform precipitation precursors due supersaturation residual solvents at very low temperature, while same time...
Organic solar cells (OSCs) with inverted structure usually exhibit higher power conversion efficiency (PCE) and are more stable than corresponding devices regular configuration. Indium tin oxide (ITO) surface is often modified solution-processed low work function metal oxides, such as ZnO, serving the transparent cathode. However, defect-induced subgap states in ZnO interlayer hamper efficient charge collection performance reproducibility of OSCs. In this work, we demonstrate that...
The compositions of most lab‐based bulk‐heterojunction (BHJ) solar cells are optimized by their power conversion efficiencies (PCEs). In this report, we suggest that the should be fill‐factors (FFs) instead. With optimized‐FF approach, BHJ tend to have higher acceptor contents and possess better thermal operational stabilities. Three model systems, namely, PTB7:PC 71 BM, PTB7‐Th:ITIC, PBDB‐T:ITIC BHJs, chosen as case studies. Charge carrier transport measurements used reveal origin enhanced...
Vacuum-assisted thermal annealing not only could improve film morphology and crystallinity, but also accelerate the sublimation of undesired MACl. With help this process, we obtain a highly efficient low-bandgap CH<sub>3</sub>NH<sub>3</sub>Sn<sub>0.5</sub>Pb<sub>0.5</sub>I<italic>x</italic>Cl<sub>3−x</sub>perovskite solar cell with power conversion efficiency 12.3%.
Abstract Ruddlesden–Popper perovskite (RPP) materials have attracted great attention due to their superior stability, where the organic spacer dominantly determines stability and efficiency of RPP solar cells, but research still lacks systematical understanding interplay binary in overall mixture range 0–100% RPPs on precursor chemistry, film quality, carrier behavior. Herein, a series novel films (PBA 1− x BA ) 2 MA 3 Pb 4 I 13 (BA = n ‐butylammonium, PBA 4‐phenylbutan‐1‐aminium,...
As one of the most promising hole‐transporting materials for perovskite solar cells (PSC), NiO is widely used in inverted p–i–n cell structure due to its high stability, decent hole conductivity, and easy processability hysteresis‐free cells. However, efficiency NiO‐based PSCs still low, largely poor perovskite/NiO interface. Herein, a sulfur‐doping strategy modify surface via ion exchange reaction by simple scalable chemical bath deposition technique introduced, which greatly improves...
A new class of hole-transporting spirothioxanthene derivatives has been synthesized and characterized. Their photophysical, electrochemical thermal properties have studied. These compounds exhibit high hole mobilities up to 1 × 10–3 cm2 V–1 s–1, determined by using thin film transistor technique. In addition, these are promising donor materials in the construction performance organic photovoltaic (OPV) devices. With a very low dopant concentration 7%, highly efficient small molecule-based...