Stabilized tilted-octahedra halide perovskites inhibit local formation of performance-limiting phases
Tiarnan A. S. Doherty, Satyawan Nagane, Dominik J. Kubicki, Young‐Kwang Jung, Duncan N. Johnstone, Affan N. Iqbal, Dengyang Guo, Kyle Frohna, Mohsen Danaie, Elizabeth M. Tennyson, Stuart Macpherson, Anna Abfalterer, Miguel Anaya, Yu‐Hsien Chiang, Phillip Crout, Francesco Simone Ruggeri, Sean M. Collins, Clare P. Grey, Aron Walsh, Paul A. Midgley, Samuel D. Stranks
Abstract
Stable but not quite cubic The black, photoactive phase of formamidinium (FA) perovskites, which is usually stabilized by cation alloying to avoid the formation of inactive hexagonal phases, is assumed to be cubic. High-resolution microscopy studies by Doherty et al . using nanoscale probes revealed that these FA-rich phases are not cubic but rather undergo slight tilting (by two degrees) of the octahedra. Black phases can have localized regions of hexagonal phases that nucleate degradation. Surface-bound ethylenediaminetetraacetic acid stabilized the tilted phase of pure FA lead triiodide against environmental degradation. —PDS