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Simultaneous Optimization of Phase and Morphology of CsPbBr 3 Films via Controllable Ostwald Ripening by Ethylene Glycol Monomethylether/Isopropanol Bi‐Solvent Engineering
Author(s) -
Meng Qingxiao,
Feng Jianyong,
Huang Huiting,
Han Xiaopeng,
Zhu Zhi,
Yu Tao,
Li Zhaosheng,
Zou Zhigang
Publication year - 2020
Publication title -
advanced engineering materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 114
eISSN - 1527-2648
pISSN - 1438-1656
DOI - 10.1002/adem.202000162
Subject(s) - ostwald ripening , materials science , chemical engineering , ethylene glycol , phase (matter) , perovskite (structure) , solvent , nanotechnology , organic chemistry , chemistry , engineering
Both phase and morphology of perovskite films are very important for high‐performance optoelectronic devices. Although a two‐step method based on CsBr ethylene glycol monomethylether (EGME) solution can prepare pure‐phase CsPbBr 3 films, they have a poor morphology due to excessive Ostwald ripening. Herein, a bi‐solvent engineering strategy is demonstrated to simultaneously optimize phase and morphology of CsPbBr 3 films in a two‐step solution method, which uses the bi‐solvents of EGME and isopropanol (IPA) instead of EGME for CsBr solution at the second step. Optimizing the volume ratio of bi‐solvents and immersion time can control the Ostwald ripening effectively and result in pure‐phase, compact, and smooth CsPbBr 3 films. Finally, the prepared films are applied to perovskite solar cells (PSCs) with a structure of fluorine‐doped tin oxide (FTO)/compact TiO 2 (c‐TiO 2 )/CsPbBr 3 /carbon. In comparison with EGME, the champion power conversion efficiency (PCE) of devices from EGME/IPA bi‐solvents increases from 3.57% to 7.29% owing mainly to higher coverage, smoother surface, and lower trap density of CsPbBr 3 films from EGME/IPA bi‐solvents. This work provides a simple and efficient method for the preparation of high‐quality CsPbBr 3 films.