Efficient post-treatment of CsPbBr3 film with enhanced photovoltaic performance

•Performance of CsPbBr3 PSC can be enhanced by organic salt FABr post-treatment.•FABr post-treatment induces passivation of grain boundaries with a generated second phase (FAyCs4−yPbBr6).•FABr post-treatment improves energy level alignment of CsPbBr3 PSC.•FABr post-treatment does not sacrifice stabi...

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Bibliographic Details
Published in:Journal of alloys and compounds 2021-08, Vol.872, p.159601, Article 159601
Main Authors: Lou, Junjie, Cai, Bing, Wu, Yihui, Lv, Yinhua, Liu, Xinhang, Zhang, Wen-Hua, Qin, Yong
Format: Article
Language:English
Subjects:
Cesium
Charge materials
Charge transport
CsPbBr3 perovskite solar cell
Energy conversion efficiency
Energy level match
Energy levels
Formamidinium bromide
Grain boundaries
Grain boundaries passivation
Ion exchange
Perovskites
Photovoltaic cells
Solar cells
Stability
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Summary:•Performance of CsPbBr3 PSC can be enhanced by organic salt FABr post-treatment.•FABr post-treatment induces passivation of grain boundaries with a generated second phase (FAyCs4−yPbBr6).•FABr post-treatment improves energy level alignment of CsPbBr3 PSC.•FABr post-treatment does not sacrifice stability of CsPbBr3. [Display omitted] All-bromide inorganic perovskite CsPbBr3 has attracted enormous attention due to its excellent stability against thermal and high humidity environmental conditions. The wide bandgap of CsPbBr3 (2.3 eV) makes it a promising material for tandem and semitransparent solar cells. However, cesium based inorganic perovskite solar cells (PSCs) usually suffer from low device performance because of their imperfect film quality and mismatched energy levels with respect to charge transport materials. Herein, we describe a post-treatment strategy for CsPbBr3 films using formamidinium bromide (FABr). With this protocol, FA+ can partially substitute Cs+ in the bulk phase of CsPbBr3, improving energy level alignment and enhancing charge extraction. Meanwhile, grain boundaries could be effectively passivated by a second phase (FAyCs4−yPbBr6) generated in the ion exchange reaction. As a result, FABr-treated PSC exhibits a champion power conversion efficiency (PCE) of 8.25%, much higher than the pristine device with PCE of 6.74%. This work provides a feasible method to improve device performance of CsPbBr3 PSCs while maintaining their outstanding stability.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2021.159601