报告题目1： Photovoltaic enhancement accompanied by polar-instability BiFeO3 vs MAPbI3
报告1内容：Ferroelectric materials for photovoltaics have sparked interest recently due to their high photovoltages. However, the relatively low photocurrent and power conversion efficiency limit their potential applications. The recently discovered hybrid perovskite MAPbI3, in which a giant photostrictive effect similar to that in ferroelectric oxides has been observed , offers a potential avenue to improve the ferroelectric photovoltaic effect. It was suggested that the dynamic polar A-site group in MAPbI3 play a critical role for their ultra-long carrier lifetime. We have investigated the hypothesis using an inorganic perovskite, BiFeO3. By engineering its A site via La doping, BiFeO3 displays large photovoltaic enhancement and polar-instability simultaneously. The improvement is attributed to the longer photocarrier lifetime as revealed by optical measurements and supported by theoretical calculations. Such polar-instability-driven band structure tuning may guide future materials design to maintain the momentum of photovoltaic efficiency increase. In addition, we investigate the effects on the carrier lifetime from a subtle direct to indirect band gap transition induced by A-site doping.
, “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).
, “Photovoltaic enhancement accompanied by polar-instability”, 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*, Science Advances (2018).
报告人1简介：Professor WANG Junling （王峻岭）obtained his B.S. degree from Nanjing University in 1999, and Ph.D. degree from University of Maryland, College Park in 2005. After spending one year at PennState University as a postdoc, he joined Nanyang Technological University, Singapore as an Assistant Professor in 2006. He was promoted to Associate Professor with tenure in 2011 and Professor in 2017. Professor Wang’s research activities focus on 3D and 2D multiferroic materials. These materials possess a wide range of exotic properties such as ferroelectricity, ferromagnetism, and multiferroicity. The long-range orders and cross-couplings between them lead to fascinating physics and various applications. He has published 130 papers in high impact journals, including Science, Nature Communications, NPG Asia Materials, Advanced Materials, PRB and APL. His work has been cited more than 9200 times.
报告题目2：Heterostructure-Based Photodetection from Mid-Infrared, Visible, to X-ray
报告2内容：Light-matter interaction is a long-lasting theme in condensed matter physics. I will discuss the use of oxide, perovskite and mixed-dimensional heterostructures with proper bandgaps and architectures to detect photons with different wavelengths. First, for visible light detection, we demonstrate that combining 3D hybrid perovskites with high-mobility 1D carbon nanotubes or 2D two-dimensional metal dichalcogenides significantly enhances charge transport and device performance [1,2]. Second, we report a mid-infrared (up to 10 um) hybrid graphene photodetector enabled via coupling graphene with a narrow bandgap semiconductor Ti2O3. Finally, using epitaxial ferroelectric/semiconductor oxide junctions with a current-perpendicular-to-plane geometry, we achieve a colossal persistent X-ray-induced photoconductivity .
.F. Li, et al., Advanced Materials, 2017, 29, 1602432.
.C. Ma, et al., Advanced Materials, 2016, 28, 3683.
.W. J. Hu, et al., Advanced Functional Materials, 2018, DOI: DOI: 10.1002/adfm.201704337
报告人2简介：Dr. Tom Wu (吴韬) received his B.S. degree from Zhejiang University in 1995 and Ph.D. degree from the University of Maryland, College Park in 2002. Before joining University of New South Wales (UNSW) in Sydney as a full professor, he worked as postdoc in Argonne National Laboratory in Chicago, assistant professor in Nanyang Technological University (NTU) Singapore, and associate professor in King Abdullah University of Science and Technology (KAUST). Dr. Wu has authored 240 peer-reviewed papers in the areas of oxide thin films, nanomaterials, and hybrid perovskites, with a focus on their electronic, magnetic and optical functionalities. His group has witnessed the career development of 14 PhD students and 25 postdocs. He also serves as an Associate Editor for ACS Applied Materials & Interfaces.