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LiTFSI‐Free Spiro‐OMeTAD‐Based Perovskite Solar Cells with Power Conversion Efficiencies Exceeding 19%
Author(s) -
Tan Boer,
Raga Sonia R.,
Chesman Anthony S. R.,
Fürer Sebastian O.,
Zheng Fei,
McMeekin David P.,
Jiang Liangcong,
Mao Wenxin,
Lin Xiongfeng,
Wen Xiaoming,
Lu Jianfeng,
Cheng YiBing,
Bach Udo
Publication year - 2019
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201901519
Subject(s) - materials science , dopant , perovskite (structure) , conductivity , lithium (medication) , doping , chemical engineering , energy conversion efficiency , salt (chemistry) , nanotechnology , optoelectronics , organic chemistry , chemistry , medicine , engineering , endocrinology
To date, the most efficient perovskite solar cells (PSCs) employ an n–i–p device architecture that uses a 2,2′,7,7′‐tetrakis( N , N ‐di‐p‐methoxyphenyl‐amine)‐9,9′‐spirobifluorene (spiro‐OMeTAD) hole‐transporting material (HTM), which achieves optimum conductivity with the addition of lithium bis(trifluoromethane)sulfonimide (LiTFSI) and air exposure. However, this additive along with its oxidation process leads to poor reproducibility and is detrimental to stability. Herein, a dicationic salt spiro‐OMeTAD(TFSI) 2 , is employed as an effective p‐dopant to achieve power conversion efficiencies of 19.3% and 18.3% (apertures of 0.16 and 1.00 cm 2 ) with excellent reproducibility in the absence of LiTFSI and air exposure. As far as it is known, these are the highest‐performing n–i–p PSCs without LiTFSI or air exposure. Comprehensive analysis demonstrates that precise control of the proportion of [spiro‐OMeTAD] + directly provides high conductivity in HTM films with low series resistance, fast hole extraction, and lower interfacial charge recombination. Moreover, the spiro‐OMeTAD(TFSI) 2 ‐doped devices show improved stability, benefitting from well‐retained HTM morphology without forming aggregates or voids when tested under an ambient atmosphere. A facile approach is presented to fabricate highly efficient PSCs by replacing LiTFSI with spiro‐OMeTAD(TFSI) 2 . Furthermore, this study provides an insight into the relationship between device performance and the HTM doping level.