Detail:

Abstract:
　　The past few years witnessed the explosion of research on photovoltaic cells based on the hybrid lead halide perovskites, in particular CH₃NH₃PbI₃. Despite the tremendous progress in device performance, much less is known about the underlying mechanism except that the carrier lifetime and diffusion length are astonishingly long in both thin films and single crystals.
　　We recently observed a giant photostrictive response, i.e., light-induced dimension change, of more than 1200 ppm in CH₃NH₃PbI₃. This is very similar to what has been observed in conventional ferroelectric oxides. However, the hybrid lead halide perovskites are not ferroelectric despite the large dipole of the CH₃NH₃ group. On the other hand, in conventional oxide perovskite BiFeO₃ with strong ferroelectricity, we observed that the photovoltaic response could be significantly improved by destabilizing the polarization. Combining these observations, we propose a model to explain the photostriction of CH₃NH₃PbI₃, and suggest a strategy to improve the photovoltaic property of conventional ferroelectric materials.

Reference:
[1], “Giant Photostriction in Organic-Inorganic Lead Halide Perovskites”, Yang Zhou†, Lu You†, Zhiliang Ku, Hongjin Fan, Shiwei Wang, Daniel Schmidt, Andrivo Rusydi, Lei Chang, Le Wang, Peng Ren, Liufang Chen, Guoliang Yuan, and Junling Wang*, Nature Communications 7:11193, doi: 10.1038/ncomms11193, (2016).
[2], “Photovoltaic enhancement accompanied by polar-instability: An insight from ferroelectric perovskite solar cells”, Lu You, Fan Zheng, Liang Fang, Yang Zhou, Liang Z. Tan, Zeyu Zhang, Guohong Ma, Daniel Schmidt, Andrivo Rusydi, Le Wang, Peng Ren, Shiwei Wang, Lei Chang, Andrew M. Rappe*, Junling Wang*, submitted (2016).

Biosketch：
　　Professor WANG Junling obtained his B.S. degree from Nanjing University in 1999, and Ph.D. degree from University of Maryland, College Park in 2005. After spending 1.5 years at Pennsylvania State University as a postdoc, he joined Nanyang Technological University, Singapore as an Assistant Professor in 2006. In 2011, he was promoted to Associate Professor with tenure.
　　Professor Wang Junling’s research activities focus on multifunctional thin films and their applications in nanoelectronic and spintronic devices. In particular, he is interested in perovskites with the chemical formula of ABX3. These materials possess a wide range of exotic properties ranging from highly insulating to superconducting, from dielectric to ferroelectric and multiferroic. He has published over 100 papers in high impact journals, including Science, Nature Communications, NPG Asia Materials, Advanced Materials, PRB and APL. His work has been cited more than 7300 times.