title: Iodomethane-Mediated Organometal Halide Perovskite with Record Photoluminescence Lifetime.
abstract: Organometallic lead halide perovskites are excellent light harvesters for high-efficiency photovoltaic devices. However, as the key component in these devices, a perovskite thin film with good morphology and minimal trap states is still difficult to obtain. Herein we show that by incorporating a low boiling point alkyl halide such as iodomethane (CH3I) into the precursor solution, a perovskite (CH3NH3PbI3-xClx) film with improved grain size and orientation can be easily achieved. More importantly, these films exhibit a significantly reduced amount of trap states. Record photoluminescence lifetimes of more than 4 μs are achieved; these lifetimes are significantly longer than that of pristine CH3NH3PbI3-xClx films. Planar heterojunction solar cells incorporating these CH3I-mediated perovskites have demonstrated a dramatically increased power conversion efficiency compared to the ones using pristine CH3NH3PbI3-xClx. Photoluminescence, transient absorption, and microwave detected photoconductivity measurements all provide consistent evidence that CH3I addition increases the number of excitons generated and their diffusion length, both of which assist efficient carrier transport in the photovoltaic device. The simple incorporation of alkyl halide to enhance perovskite surface passivation introduces an important direction for future progress on high efficiency perovskite optoelectronic devices.
authors.affiliation: Jiangsu Key Laboratory of Carbon-Based Materials, Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University , Suzhou, Jiangsu 215123, China.
authors.forename: Weidong
authors.initials: W
authors.lastname: Xu
authors.affiliation: Jiangsu Key Laboratory of Carbon-Based Materials, Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University , Suzhou, Jiangsu 215123, China.
authors.forename: John A
authors.initials: JA
authors.lastname: McLeod
authors.affiliation: Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences , Shanghai, 201204, China.
authors.forename: Yingguo
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Institute of Information Photonic Technology and College of Applied Sciences, Beijing University of Technology , Beijing, 100124, China.
authors.forename: Yimeng
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Jiangsu Key Laboratory of Carbon-Based Materials, Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University , Suzhou, Jiangsu 215123, China.
authors.forename: Zhongwei
authors.initials: Z
authors.lastname: Wu
authors.affiliation: Department of Physics, Chemistry and Biology (IFM), Linköping University, Campus Valla , Linköping, SE-58183, Sweden.
authors.forename: Sai
authors.initials: S
authors.lastname: Bai
authors.affiliation: Department of Physics, Chemistry and Biology (IFM), Linköping University, Campus Valla , Linköping, SE-58183, Sweden.
authors.forename: Zhongcheng
authors.initials: Z
authors.lastname: Yuan
authors.affiliation: Jiangsu Key Laboratory of Carbon-Based Materials, Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University , Suzhou, Jiangsu 215123, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Song
authors.affiliation: Jiangsu Key Laboratory of Carbon-Based Materials, Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University , Suzhou, Jiangsu 215123, China.
authors.forename: Yusheng
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Silicon Materials, Cyrus Tang Center for Sensor Materials and Applications, Department of Materials Science and Engineering, Zhejiang University , Hangzhou, 310027, China.
authors.forename: Junjie
authors.initials: J
authors.lastname: Si
authors.affiliation: Jiangsu Key Laboratory of Carbon-Based Materials, Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University , Suzhou, Jiangsu 215123, China.
authors.forename: Rongbin
authors.initials: R
authors.lastname: Wang
authors.affiliation: Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences , Shanghai, 201204, China.
authors.forename: Xingyu
authors.initials: X
authors.lastname: Gao
authors.affiliation: Institute of Information Photonic Technology and College of Applied Sciences, Beijing University of Technology , Beijing, 100124, China.
authors.forename: Xinping
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Jiangsu Key Laboratory of Carbon-Based Materials, Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University , Suzhou, Jiangsu 215123, China.
authors.forename: Lijia
authors.initials: L
authors.lastname: Liu
authors.affiliation: Jiangsu Key Laboratory of Carbon-Based Materials, Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University , Suzhou, Jiangsu 215123, China.
authors.forename: Baoquan
authors.initials: B
authors.lastname: Sun
keywords: iodomethane; microwave detected photoconductivity; perovskite solar cell; photoluminescence lifetime; surface passivation; transient absorption; trap state