报告人：张燮

报告题目：Understanding light-induced efficiency enhancement in hybrid-perovskite solar cells

报告摘要：It was observed in recent experiments that light exposure could induce pronounced lattice expansion of hybrid perovskites, which in turn enhances the power conversion efficiency of perovskite solar cells by a few per cent. However, the mechanism behind the efficiency enhancement is still unclear. Employing our recently developed methodology for computing defect-assisted nonradiative recombination rates to hybrid perovskite FAPbI3, we show that 1% lattice expansion could decrease the nonradiative capture coefficient by one order of magnitude, drastically extending the carrier lifetime. More interestingly, the decrease is actually not caused by changes in the band gap or defect transition level a result of lattice expansion, but stems from enhanced defect relaxations in the expanded lattice. Our insights not only rationalize the puzzling experimental observation, but also offer a widely applicable pathway to tune nonradiative recombination through light-matter coupling.

报告简介：张燮，中国工程物理研究院北京计算科学研究中心特聘研究员，2019年国家海外高层次青年人才计划入选者。2015年取得德国马普钢铁研究所和鲁尔波鸿大学博士学位（导师：Jörg Neugebauer教授）。曾先后在德国马普钢铁研究所和美国加州大学圣芭芭拉分校材料系（导师：Chris G. Van de Walle院士）从事博士后研究，并于2020年11月全职回国。专注于先进结构与能源材料中缺陷与相变的第一性原理研究。近年来在Nat. Mater., Nat. Commun., Sci. Adv., Phys. Rev. Lett., Adv. Energy Mater.等国际一流期刊发表研究论文数十篇。2018年获得加州大学圣芭芭拉分校固态发光与能源电子中心杰出研究成就奖。2019年获美国能源部国家能源研究科学计算中心所颁发的高影响力科学计算青年成就奖。