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Morphology Control of Doped Spiro‐MeOTAD Films for Air Stable Perovskite Solar Cells
Author(s) -
Wang Sisi,
Wei Qi,
Wang Kaiyang,
Zhang Zhipeng,
Zhao Dandan,
Liang Chao,
Liu Tanghao,
Guo Jia,
Su Chenliang,
Li Ying,
Xing Guichuan
Publication year - 2020
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201907513
Subject(s) - materials science , dopant , moisture , chemical engineering , annealing (glass) , energy conversion efficiency , doping , lithium (medication) , nanocrystal , nanotechnology , composite material , optoelectronics , medicine , engineering , endocrinology
Doped 2,2′,7,7′‐tetrakis( N , N ‐di‐ p ‐methoxyphenylamine)‐9,9′‐spirobifluorene (spiro‐MeOTAD), which acts as a hole‐transporting layer (HTL), endows perovskite solar cells (PSCs) with excellent performance. However, the intrinsically hygroscopic nature of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) dopants also aggravates the moisture instability of PSCs. In this work, the origins of the moisture instability of spiro‐MeOTAD HTLs are explored and strategies to enhance moisture resistance are proposed. After 780 h of aging in air, 52% of the initial power conversion efficiency (PCE) can be sustained by prolonging the mixing time of the precursor solution of spiro‐MeOTAD to reduce accumulated LiTFSI. In contrast, only 7% of the initial PCE remains if the precursor solution is mixed briefly. By thermally annealing an HTL to evaporate residual tBP in spiro‐MeOTAD, pinholes are completely eliminated and 65% of the initial PCE remains after the same aging time. In this study, the significance of the initial morphology of spiro‐MeOTAD HTLs on device stability is analyzed and strategies based on physical morphology for controlling PSC moisture instability induced by HTL dopants are developed.