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The influence of thermal treatments on the properties of mixed bromide–iodide organolead perovskites (MAPbI3–x Br x, MA= CH3NH3) is investigated in films prepared in air by single-step solution processes based on different precursor solutions. Initially, the bandgap energy (EG) dependence on composition is reconsidered on films obtained by mixtures of trihalide solutions. An EG (x) relation is obtained that is expected to be independent of the film properties and can be used to assess perovskite composition. In these samples, recombination centers are observed whose energy depth increases with x, likely involving the simultaneous presence of iodide and bromide, while the Urbach energy increases with the grain surface-to-volume ratio, which points out that the defects giving sub-bandgap absorption originate from grain boundaries. Trihalide mixtures allow perovskite synthetic …
American Chemical Society
Publication date: 
3 Sep 2015

Paolo Fedeli, Francesco Gazza, Davide Calestani, Patrizia Ferro, Tullo Besagni, Andrea Zappettini, Gianluca Calestani, Enrico Marchi, Paola Ceroni, Roberto Mosca

Biblio References: 
Volume: 119 Issue: 37 Pages: 21304-21313
The Journal of Physical Chemistry C