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We study the mechanisms of CH {sub 3} NH {sub 3} PbI {sub 3} degradation and its transformation to PbI {sub 2} by means of X-ray diffraction and the density functional theory. The experimental analysis shows that the material can degrade in both air and vacuum conditions, with humidity and temperature-annealing strongly accelerating such process. Based on ab initio calculations, we argue that even in the absence of humidity, a decomposition of the perovskite structure can take place through the statistical formation of molecular defects with a non-ionic character, whose volatility at surfaces should break the thermodynamic defect equilibria. We finally discuss the strategies that can limit such phenomenon and subsequently prolong the lifetime of the material.
Publication date: 
30 Mar 2015

I Deretzis, A Alberti, G Pellegrino, E Smecca, F Giannazzo, A La Magna, N Sakai, T Miyasaka

Biblio References: 
Volume: 106 Issue: 13
Applied Physics Letters