A Multifunctional Liquid Crystal as Hole Transport Layer Additive Enhances Efficiency and Stability of Perovskite Solar Cells |
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Authors: | Qian Lai Rongshan Zhuang Kun Zhang Tai Wu Lin Xie Dr Rongjun Zhao Lei Yang Prof Yang Wang Prof Yong Hua |
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Institution: | 1. School of Materials and Energy, Yunnan University, 650091 Kunming, China
These authors contributed equally to this work.;2. Key Laboratory of Green Printing, Institute of Chemistry, Chinese Academy of Sciences, 100190 Beijing, P. R. China
These authors contributed equally to this work.;3. School of Materials and Energy, Yunnan University, 650091 Kunming, China;4. Key Laboratory of Green Printing, Institute of Chemistry, Chinese Academy of Sciences, 100190 Beijing, P. R. China |
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Abstract: | Lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) has been identified as the most used and effective p-dopant for hole transport layer (HTL) in perovskite solar cells (PSCs). However, the migration and agglomeration of Li-TFSI in HTL negatively impact PSCs performance and stability. Herein, we report an effective strategy for adding a liquid crystal organic small molecule (LQ) into Li-TFSI doped (2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′- spirobifluorene (Spiro-OMeTAD) HTL. It was found that the introduction of LQ into Spiro-OMeTAD HTL can efficiently enhance the charge carrier extraction and transportation in device, which can strongly retard the charge carrier recombination in device. Consequently, the PSCs efficiency is significantly enhanced to 24.42 % (Spiro-OMeTAD+LQ) from 21.03 % (Spiro-OMeTAD). The chemical coordination between LQ and Li-TFSI can strongly confine Li+ ions migration and agglomeration of Li-TFSI, thus, achieving the enhanced device stability. Only a 9 % efficiency degradation is observed for un-encapsulated device prepared with Spiro-OMeTAD and LQ after 1700 h under air environment, while the efficiency drops by 30 % for the reference device. This work provides an effective strategy for improving the efficiency and stability of PSCs, and gives some important insights for understanding intrinsic hot carriers dynamics for perovskite-based optoelectronic devices. |
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Keywords: | Charge Recombination Hole Transport Layer Li+ Ion Migration Perovskite Solar Cells |
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