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Side‐Chain Engineering on Dopant‐Free Hole‐Transporting Polymers toward Highly Efficient Perovskite Solar Cells (20.19%)
Author(s) -
Zhang Luozheng,
Liu Chang,
Wang Xingzhu,
Tian Yanqing,
Jen Alex K. Y.,
Xu Baomin
Publication year - 2019
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201904856
Subject(s) - materials science , dopant , perovskite (structure) , energy conversion efficiency , side chain , layer (electronics) , lamellar structure , chemical engineering , photovoltaic system , polymer , nanotechnology , doping , optoelectronics , composite material , ecology , engineering , biology
A variety of dopant‐free hole‐transporting materials (HTMs) is developed to serve as alternatives to the typical dopant‐treated ones; however, their photovoltaic performance still falls far behind. In this work, the side chain of a polymeric HTM is engineered by partially introducing diethylene glycol (DEG) groups in order to simultaneously optimize the properties of both the bulk of the HTM layer and the HTM/perovskite interface. The intermolecular π–π stacking interaction in the HTM layer is unexpectedly weakened after the incorporation of DEG groups, whereas the lamellar packing interaction is strengthened. A doubled hole mobility is obtained when 3% of the DEG groups replace the original alkyl side chains, and a champion power conversion efficiency (PCE) of 20.19% (certified: 20.10%) is then achieved, which is the first report of values over 20% for dopant‐free organic HTMs. The device maintains 92.25% of its initial PCE after storing at ambient atmosphere for 30 d, which should be due to the enhanced hydrophobicity of the HTM film.