New Schemes of Room-Temperature Solution-Processed Carrier Transport Layers and Transparent Flexible Electrode for High Performance Optoelectronic Devices
Speaker:Prof. Wallace C. H. Choy
Associate Professor
Department of Electrical and Electronic Engineering
The University of Hong Kong, Hong Kong
Date & Time:2 Nov 2015 (Monday) 11:00
Organized by:Institute of Applied Physics and Materials Engineering


Carrier (electron and hole) transport layers are important components in organic/inorganic optoelectronics such as organic solar cells (OSCs), perovskite solar cells, dye sensitized solar cells, organic light emitting diodes, etc which can favor the efficient transport of carriers between the photoactive layer and electrode as well as high optical transparency. Transition metal oxides are promising materials for carrier transport layers because of their good electrical properties, stability, and optical transmission. We propose and demonstrate several low-temperature solution-processed approaches for forming transparent and efficient metal oxide-based carrier transport layers including electron and hole transport layers. With the incorporation of metal nanoparticles, the electrical and optical properties can be enhanced. The interesting features of the novel carrier extraction layers are low temperature (i.e. low cost), solution process (i.e. large area) and water free (i.e. compatible to most devices) for high performance optoelectronics such as OSCs with power conversion efficiency (PCE) of 10.5%. In addition, we have developed some room-temperature processed Ag nano-network which can serve as transparent flexible electrodes, With the knowledge of solution processed organic and inorganic materials, we have recently proposed different approaches such as vacuum-Assisted thermal annealing of CH3NH3PbI3 for highly stable and efficient perovskite SCs with PCE of 17.5% and no hysteresis.


Prof. Wallace Choy received Ph.D Degree in Electronic Engineering from University of Surrey, UK in 1999. After vigorous working experiences in National Research Council of Canada and Fujitsu at San Jose, on investigating optoelectronic devices, he is now an associate professor of Department of Electrical and Electronic Engineering, the University of Hong Kong. His current research interests are concerned with organic/inorganic optoelectronic devices, plasmonic structures, and nano-material devices and physics. Prof. Choy has been recognized as the Top 1% of most-cited scientists in Thomson Reuter's Essential Science Indicators (ESI) in 2014 and 2015. Prof. Choy has published over 150 internationally peer-reviewed journal papers (details of publications:, contributed to seven book chapters, US and China patents and edited one book published in Springer. He has served as Editorial Board Member for Nature Publishing Group of Scientific Reports (Apr 2015-present), topical editor of OSA Journal of the Optical Society of America B (JOSA founded in 1917), associate editor of IEEE Photonic Journals and guest editor of OSA Journal of Photonic Research, and Journal of Optical Quantum Electronics. He is now a senior member of IEEE.