Solid-State Growth of Cspbi3 Perovskites: Phases Formation and Stability

Abstract

Abstract Totally inorganic perovskites are playing an increasingly important role for their potential applications in optoelectronics devices. However, a big problem to be solved is the role of the different phases, the presence of which is closely linked to the growth method and to the role of impurities. In this article, we propose a solvent-free, solid-state growth method, which allows to obtain samples free of any organic residues. The analysis of structural (XRD and Raman measurements), optical (absorption, steady-time and time-resolved luminescence) and morphological (HRTEM imaging), permitted to understand the phase evolution during the synthesis as a function of the temporal duration. The dynamic equilibrium process at high temperature between the CsPbI3 and the starting precursors, CsI and PbI2, plays a fundamental role in the final phase. If, from one side, the α and δ phases are related to the exact stoichiometry, on the other hand an excess of CsI permits the formation of room temperature stable perovskite γ-phase and, with a further excess, the secondary Cs4PbI6 phase is obtained.