Effect of mechanical forces on thermal stability reinforcement for lead based perovskite materials

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2019, Vol.7 (2), p.540-548
• Main Authors: Ding, Dong, Li, Henan, Li, Jieni, Li, Zibo, Yao, Huizhen, Liu, Lai, Tian, Bing Bing, Su, Chenliang, Chen, Fuming, Shi, Yumeng
• Format: Article
• Language: English
• Subjects: Dry grinding; Environmental factors; Grinding; High temperature environments; Materials recovery; Optoelectronic devices; Oxygen; Perovskites; Powder; Pressure; Quantitative research; Thermal stability
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/C8TA08868C

Stability is one of the major challenges of organic–inorganic hybrid perovskite materials (APbX 3 , where A = MA + , FA + and Cs + , and X = I − , Br − and Cl − , respectively) in optoelectronic device applications. APbX 3 materials are extremely sensitive to temperature, humidity and oxygen. Although degradation of the materials caused by oxygen and moisture could be partially solved by encapsulation techniques, further improving the stability of perovskites under external heat is still demanding. Generally, APbX 3 would decompose into AX and PbX 2 at the early stage, when it is in a high-temperature environment. In this contribution, we demonstrated that pressure can reinforce the thermal stability of MAPbX 3 , by promoting the reverse reaction. The stability reinforcement of MAPbI 3 by mechanical forces was found to be more effective compared with that of MAPbBr 3 /MAPbCl 3 . Furthermore, we carried out quantitative research to mimic pressure induced reverse reactions, through dry-grinding the powder mixtures of equimolar PbX 2 and AX. We found that the conversion yields and reaction paths were dramatically different depending on the type of organic-cation (A) and halide (X). APbI 3 , CsPbBr 3 and CsPbCl 3 can be directly and completely synthesized by the dry grinding method, and thus they are more promising candidates for material recovery by external forces. Meanwhile, it was found that CsPbBr 3 and CsPbCl 3 crystalize via Cs 4 PbX 6 (X = Br or Cl) intermediate states. Our results provide a robust strategy for the specific design of perovskite material based optoelectronic devices, especially for applications demanding better stability.