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Effect of Formamidinium/Cesium Substitution and PbI 2 on the Long‐Term Stability of Triple‐Cation Perovskites
Author(s) -
Shukla Shashwat,
Shukla Sudhanshu,
Haur Lew Jia,
Dintakurti Sai S. H.,
Han Guifang,
Priyadarshi Anish,
Baikie Tom,
Mhaisalkar Subodh G.,
Mathews Nripan
Publication year - 2017
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201701203
Subject(s) - formamidinium , perovskite (structure) , halide , caesium , kinetics , chemistry , degradation (telecommunications) , absorption (acoustics) , chemical engineering , materials science , inorganic chemistry , crystallography , telecommunications , physics , quantum mechanics , computer science , engineering , composite material
Altering cation and anion ratios in perovskites has proven an excellent means of tuning the perovskite properties and enhancing the performance. Recently, methylammonium/formamidinium/cesium triple‐cation mixed‐halide perovskites have demonstrated efficiencies up to 22 %. Similar to the widely explored methylammonium lead halide, excess PbI 2 is added to these perovskite films to enhance their performances. The excess PbI 2 is known to be beneficial for the performance. However, its impact on stability is less well known. Triple‐cation perovskites deploy excess PbI 2 up to 8 %. Thus, it is imperative to analyze the role of excess PbI 2 in the degradation kinetics. In this study, the amount of PbI 2 in the triple‐cation perovskite films is varied and the degradation kinetics monitored by X‐ray diffraction and optical absorption spectroscopy. The inclusion of excess PbI 2 is shown to adversely affect the stability of the material. Faster degradation kinetics are observed for samples with higher PbI 2 contents. However, samples with excess PbI 2 also showed superior properties such as enhanced grain sizes and better optical absorption. Thus, careful management of the PbI 2 quantity is required to obtain better stability and alternative pathways should be explored to achieve better device performance rather than adding excess PbI 2 .