title: Mechanism of biphasic charge recombination and accumulation in TiO2 mesoporous structured perovskite solar cells.
abstract: Organic-inorganic halide perovskite solar cells are becoming the next big thing in the photovoltaic field owing to their rapidly developing photoelectric conversion performance. Herein, mesoporous structured perovskite devices with various perovskite grain sizes are fabricated by a sequential dropping method, and the charge recombination dynamics is investigated by transient optical-electric measurements. All devices exhibit an overall power conversion efficiency around 15%. More importantly, a biphasic trap-limited charge recombination process is proposed and interpreted by taking into account the specific charge accumulation mechanism in perovskite solar cells. At low Fermi levels, photo-generated electrons predominately populate in the perovskite phase, while at high Fermi levels, most electrons occupy traps in mesoporous TiO2. As a result, the dynamics of charge recombination is, respectively, dominated by the perovskite phase and mesoporous TiO2 in these two cases. The present work would give a new perspective on the charge recombination process in meso-structured perovskite solar cells.
authors.affiliation: Department of Chemistry, Renmin University of China, Beijing 100872, P. R. China. yjqin@ruc.edu.cn.
authors.forename: Hao-Yi
authors.initials: HY
authors.lastname: Wang
authors.affiliation: Department of Chemistry, Renmin University of China, Beijing 100872, P. R. China. yjqin@ruc.edu.cn.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Chemistry, Renmin University of China, Beijing 100872, P. R. China. yjqin@ruc.edu.cn.
authors.forename: Man
authors.initials: M
authors.lastname: Yu
authors.affiliation: Department of Chemistry, Renmin University of China, Beijing 100872, P. R. China. yjqin@ruc.edu.cn.
authors.forename: Jun
authors.initials: J
authors.lastname: Han
authors.affiliation: Department of Chemistry, Renmin University of China, Beijing 100872, P. R. China. yjqin@ruc.edu.cn.
authors.forename: Zhi-Xin
authors.initials: ZX
authors.lastname: Guo
authors.affiliation: Department of Chemistry, Renmin University of China, Beijing 100872, P. R. China. yjqin@ruc.edu.cn.
authors.forename: Xi-Cheng
authors.initials: XC
authors.lastname: Ai
authors.affiliation: Department of Chemistry, Renmin University of China, Beijing 100872, P. R. China. yjqin@ruc.edu.cn.
authors.forename: Jian-Ping
authors.initials: JP
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, Renmin University of China, Beijing 100872, P. R. China. yjqin@ruc.edu.cn.
authors.forename: Yujun
authors.initials: Y
authors.lastname: Qin