Premium
Stabilizing Formamidinium Lead Iodide Perovskite by Sulfonyl‐Functionalized Phenethylammonium Salt via Crystallization Control and Surface Passivation
Author(s) -
Shen Chao,
Wu Yongzhen,
Zhang Shuo,
Wu Tianhao,
Tian He,
Zhu Wei-Hong,
Han Liyuan
Publication year - 2020
Publication title -
solar rrl
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.544
H-Index - 37
ISSN - 2367-198X
DOI - 10.1002/solr.202000069
Subject(s) - formamidinium , passivation , crystallization , iodide , materials science , perovskite (structure) , halide , carrier lifetime , chemical engineering , inorganic chemistry , chemistry , silicon , nanotechnology , organic chemistry , layer (electronics) , engineering , metallurgy
Bulky organic ammonium cations have been widely used to stabilize lead halide perovskites via surface passivation or dimensionality modulation. Herein, a sulfonyl fluoride‐functionalized phenethylammonium salt (SF‐PEA) is reported as a bifunctional additive to stabilize the formamidinium lead iodide (FAPbI 3 ) perovskite. The sulfonyl group is found to interact with PbI 2 in the precursor and slow down the crystallization of FAPbI 3 during thermal annealing, leading to improved crystalline quality and decreased structural defects. After annealing, the spontaneous assembly of SF‐PEA on the crystal surface of FAPbI 3 not only passivates the surface defects, but also protects the perovskite from phase transition that is caused by strain or moisture invasion. The resulting FAPbI 3 films are extremely stable, which can maintain their black phase for more than 3 months in air with 40–50% relative humidity, much better than pristine and unsubstituted phenethylammonium (PEA)‐based samples. Because of the greatly improved phase stability and crystallization quality, a champion power conversion efficiency (PCE) of 21.25% (certified PCE of 20.70%) is achieved in planar n–i–p structured solar cells, which is the highest one among “methylammonium‐free” FAPbI 3 perovskite photovoltaics.