Proceedings of Perovskite Thin Film Photovoltaics (ABXPV17)
Publication date: 18th December 2016
Issues on stability and durability of hybrid perovskites are dramatically delaying the large dissemination of low cost/high yield related technologies for photovoltaic, light sensing and emitting purposes. Thereby, the advance of the technologies is currently forced to pass through the rationalization of the phenomena occurring into the hybrid lattice under conditions which mimic the material operation. In this framework, we study the structural modifications of MAPbI3 layers by in-situ structural and optical analyses upon recursive thermal cycles from 30°C to 80°C in different annealing environments. We reveal a hitherto unknown phenomenon consisting in an acceleration of the material degradation, above what expected, as the threshold of the tetragonal to cubic transition (50°C) is surpassed. This produces discontinuities in the degradation rate, bandgap and dielectric behavior of the material. The phenomenon is put in relationship with the order-disorder lattice modifications described by Car-Parrinello molecular dynamics calculations, and reveals that the action of species from humid air becomes largely more effective above 50°C for reasons related to the increased accessibility/reactivity of the lattice which, in turn, rises defects generation.