Biography
Prof. Shuang Yang
Prof. Shuang Yang
East China University of Science and Technology, China
Title: Surface Chemistry of Perovskite Solar Cells
Abstract: 
Organic-inorganic hybrid perovskite are particularly suited as light-harvesting materials in photovoltaic devices. The power conversion efficiency of perovskite solar cells (PSCs) has reached certified values of over 25% in just a few years. However, one of the major hindrances for application of these materials in real-world devices is the performance degradation under light, moisture or high temperature, leading to a rapid loss of photovoltaic response. Firstly, we have demonstrated that hydrophobic tertiary and quaternary alkyl ammonium cations can be successfully assembled on the perovskite surface as efficient water-resisting layers via a facile surface functionalization technique. Such layers can protect the perovskite film under high relative humidity (90 ± 5%) over 30 days. More importantly, devices based on such films can retain the photovoltaic capacities of bulk perovskite with power conversion efficiencies. Then, we improved the devices’ operational lifetime by converting the surfaces of lead halide perovskite to water-insoluble lead (II) oxysalt through reaction with sulfate or phosphate ions. These capping lead oxysalt thin layers enhance the water resistance of the perovskite films by forming strong chemical bonds. The wide-bandgap lead oxysalt layers also reduce the defect density on the perovskite surfaces by passivating undercoordinated surface lead centers, which are defect-nucleating sites. Encapsulated devices stabilized by the lead oxysalt layers maintain 96.8% of their initial efficiency after operation at maximum power point under simulated air mass (AM) 1.5 G irradiation for 1200 hours at 65°C.

Keywords: perovskite, solar cell, surface chemistry, stability, efficiency

Reference
[1] Shuang Yang#, Yun Wang#, Porun Liu, Yi Bing Cheng, Hui Jun Zhao* and Hua Gui Yang*, Functionalization of perovskite thin films with moisture-tolerant molecules, Nature Energy, 2016, 1, 15016.
[2] Shuang Yang#, Shangshang Chen#, Edoardo Mosconi, Yanjun Fang, Xun Xiao, Congcong Wang, Yu Zhou, Zhenhua Yu, Jingjing Zhao, Yongli Gao, Filippo De Angelis, Jinsong Huang*, Stabilizing halide perovskite surfaces for solar cell operation with wide–bandgap lead oxysalts, Science, 2019, 6452 (365), 473-478.
Biography: 
Shuang Yang received his Bachelor degree from Tsingtao University of Science & Technology in 2011, and got his PhD degree at East China University of Science and Technology in 2016. He then joined Nanyang Technological University, University of Nesbraka- Lincoln, University of North Carlina, Chapel Hill as a postdoctoral researcher. Currently he is a professor at East Chin University of Science &Technology. His research focus on the chemistry and physics of semiconducting materials and photo-electric devices. He has published more than 50 research papers, including Science, Nat. Energy, Nat. Common., J. Am. Chem. Soc., Angew. Chem. Int. Ed., Adv. Mater. etc. His current research interests focus on semiconducting materials and next-generation photovoltaics.