Understanding the stability origins of ambient stable CsPbI2Br inorganic halide perovskites

Congtan Zhu; Feiyu Lin; Lin Zhang; Si Xiao; Shupeng Ma; Sheng Liu; Qidong Tai; Liu Zhu; Qilin Dai; Xueyi Guo; Ying Yang

doi:10.1039/D2TA01464E

Understanding the stability origins of ambient stable CsPbI₂Br inorganic halide perovskites†

Congtan Zhu,

^a Feiyu Lin,^a Lin Zhang,^a Si Xiao,

^b Shupeng Ma,^a Sheng Liu,^a Qidong Tai,^c Liu Zhu,^d Qilin Dai,

^e Xueyi Guo*^a and Ying Yang*^a

Author affiliations

* Corresponding authors

^a School of Metallurgy and Environment, Central South University, Changsha 410083, China
E-mail: muyicaoyang@csu.edu.cn, xyguo@csu.edu.cn

^b School of Physics and Electronics, Central South University, Changsha, Hunan, PR China

^c Institute of Technological Sciences, Wuhan University, Wuhan, Hubei, PR China

^d First Rare Materials Co., Ltd., Qingyuan 511517, China

^e Department of Chemistry, Physics and Atmospheric Sciences, Jackson State University, Jackson, MS, USA

Abstract

All-inorganic halide perovskites (IHPs) hold promise in the field of optoelectronics due to their excellent thermal stability. However, the phase instability of these metastable structural polymorphs needs to be addressed. Here, a great deal of interest has been emerging to understand the phase (in)stability and report an additional stability mechanism of CsPbI₂Br perovskite induced by both O₂ and moisture in dry and high humid air to develop engineering strategies for making more robust IHPs. It is demonstrated that CsPbI₂Br prepared in N₂ experiences a sharp degradation as it is exposed to air (RH = 35%), while CsPbI₂Br prepared in air shows much better long-term stability than that prepared in N₂ atmosphere in both low (RH = 5–15%) and high humidity (RH = 30–55%) environments. The participation of O₂ in the formation of perovskite crystals to form Pb–O bonds in the spin-coating process can prevent the transformation of CsPbI₂Br from the α-phase to the δ-phase. In the presence of both oxygen and moisture, it is suggested that water can stabilize the reactive superoxide, which is formed by oxygen with excess electrons and enable them to spontaneously form additional Pb–O bonds with Pb before annealing. This can further stabilize perovskite under higher humidity conditions and improve the phase stability. This work presents a material design to develop IHPs in air with high stability.

Journal of Materials Chemistry A

Understanding the stability origins of ambient stable CsPbI₂Br inorganic halide perovskites†

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Understanding the stability origins of ambient stable CsPbI₂Br inorganic halide perovskites

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Journal of Materials Chemistry A