Lei Chen1,2,§, Feng Tang2,§, Yixin Wang2,3, Shan Gao2, Weiguo Cao1, Jinhua Cai2 (*), and Liwei Chen2 (*)
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1 Department of Chemistry, Shanghai University, Shanghai 200444, China 2 i-Lab, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, Jiangsu 215123, China 3 Nano Science and Technology Institute, University of Science and Technology of China, Suzhou, Jiangsu 215123, China § These authors contributed equally to this work.
Keywords:solid-state chemistry, perovskite solar cells, planar heterojunction, flexible substrates
The power conversion efficiency of organometallic perovskite-based solar cells has skyrocketed in recent years. Intensive efforts have been made to prepare high-quality perovskite films tailored to various device configurations. Planar heterojunction devices have achieved record efficiencies; however, the preparation of perovskite films for planar junction devices requires the use of expensive vacuum facilities and/or the fine control of experimental conditions. Here, we demonstrate a facile preparation of perovskite films using solid-state chemistry. Solid-state precursor thin films of CH3NH3I and PbI2 are brought into contact with each other and allowed to react via thermally accelerated diffusion. The resulting perovskite film displays good optical absorption and a smooth morphology. Solar cells based on these films show an average efficiency of 8.7% and a maximum efficiency of 10%. The solid-state synthesis of organometallic perovskite can also be carried out on flexible plastic substrates. Using this method on a PET/ITO substrate produces devices with an efficiency of 3.2%. Unlike existing synthetic methods for organometallic perovskite films, the solid-state reaction method does not require the use of orthogonal solvents or careful adjustment of reaction conditions, and thus shows good potential for mass production in the future.