A Deformable Additive on Defects Passivation and Phase Segregation Inhibition Enables the Efficiency of Inverted Perovskite Solar Cells over 24

The defects and phase segregation in perovskite will significantly reduce the performance and stability of perovskite solar cells (PSCs). In this work, a deformable coumarin is employed as a multifunctional additive for formamidinium-cesium (FA-Cs) perovskite. During the annealing process of perovsk...

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Bibliographic Details
Published in:Advanced materials (Weinheim) 2023-09, Vol.35 (38), p.e2302752-e2302752
Main Authors: Xie, Lisha, Liu, Jian, Li, Jun, Liu, Chang, Pu, Zhenwei, Xu, Peng, Wang, Yaohua, Meng, Yuanyuan, Yang, Mengjin, Ge, Ziyi
Format: Article
Language:English
Subjects:
Bromine
Cesium
Coumarin
Crystal defects
Deformation
Energy conversion efficiency
Energy levels
Formability
Grain size
Iodine
Materials science
Perovskites
Photovoltaic cells
Residual stress
Solar cells
Stability
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Summary:The defects and phase segregation in perovskite will significantly reduce the performance and stability of perovskite solar cells (PSCs). In this work, a deformable coumarin is employed as a multifunctional additive for formamidinium-cesium (FA-Cs) perovskite. During the annealing process of perovskite, the partial decomposition of coumarin passivates the Pb , iodine, and organic cation defects. Additionally, coumarin can affect colloidal size distributions, resulting in relatively large grain size and good crystallinity of target perovskite film. Hence, the carrier extraction/transport can be promoted, trap-assisted recombination is reduced, and energy levels are optimized in target perovskite films. Furthermore, the coumarin treatment can significantly release residual stress. As a result, the champion power conversion efficiencies (PCEs) of 23.18% and 24.14% are obtained for Br-rich (FA Cs PbI Br ) and Br-poor (FA Cs PbI Br ) based devices, respectively. The flexible PSCs based on Br-poor perovskite exhibit an excellent PCE of 23.13%, one of the highest values for flexible PSCs reported to date. Due to the inhibition of phase segregation, the target devices exhibit excellent thermal and light stability. This work provides new insights into the additive engineering of passivating defects, stress relief, and inhibition of phase segregation of perovskite films, offering a reliable method to develop state-of-the-art solar cells.
ISSN:0935-9648
1521-4095
DOI:10.1002/adma.202302752