Non‐Perovskite Hybrid Material, Imidazolium Lead Iodide, with Enhanced Stability

Abstract A systematic study of a new hybrid organic‐inorganic material where the cation has been replaced with imidazolium is presented. Imidazolium lead iodide (ImPI) shares the same stoichiometry of ABX₃ as a perovskite, however, it has a hexagonal structure. This material shows a vastly improved thermal stability as compared to the more popular hybrid perovskite, methyl ammonium lead iodide (MAPI). ImPI also exhibits a dramatic phase stability as compared to MAPI as demonstrated by the variable temperature XRD data (both low temperature and high temperature). In addition to the enhanced thermal robustness, ImPI shows three times better stability than MAPI under ambient conditions. The stability can be attributed to better packing efficiency of the ImPI lattice which in turn depends on the symmetrical and bulkier organic cation, imidazolium. Optoelectronic measurements were also performed and specifically, unlike for MAPI, photoluminescence measurements of ImPI showcased a broad emission over a range of 500 nm to 900 nm which could be attributed to the presence of self‐trapped excitons and as such this broad emission holds promise for light emitting device applications.