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ACS Appl Mater Interfaces. 2016 Sep 7;8(35):23181-9. doi: 10.1021/acsami.6b05770. Epub 2016 Aug 25.

Iodomethane-Mediated Organometal Halide Perovskite with Record Photoluminescence Lifetime.

Author information

1
Jiangsu Key Laboratory of Carbon-Based Materials, Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University , Suzhou, Jiangsu 215123, China.
2
Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences , Shanghai, 201204, China.
3
Institute of Information Photonic Technology and College of Applied Sciences, Beijing University of Technology , Beijing, 100124, China.
4
Department of Physics, Chemistry and Biology (IFM), Linköping University, Campus Valla , Linköping, SE-58183, Sweden.
5
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.

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.

KEYWORDS:

iodomethane; microwave detected photoconductivity; perovskite solar cell; photoluminescence lifetime; surface passivation; transient absorption; trap state

PMID:
27529636
DOI:
10.1021/acsami.6b05770

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