Enhancing photoluminescence of manganese chloride perovskite-analogues through phase transformations induced by Sn incorporation

Herein, we develop a facile strategy to synthesize one-dimensional Sn-incorporated CsMnCl3 microcrystals (MCs) via an acid dissolution method under high humidity. The prepared CsMnCl3(H2O)α:0.50%Sn (α = 0 or 2, noted as CMCH:0.50%Sn) MCs exhibit an intense red emission assigned to 4T1g→6A1g transition of Mn2+ with a photoluminescence (PL) quantum yield (QY) of 15.77%, which is four times than that of pristine CsMnCl3(H2O)2 MCs, with an activation energy of 160 meV determined from a temperature-dependent PL Boltzmann analysis. Sn2+ ions incorporation can promote the formation of anhydrous CsMnCl3 and are likely bonded to Cl ions. A red LED device based on CMCH:0.50%Sn MCs shows ultra-high color purity at a drive current of 300 mA and good stability. This work successfully addresses the issue of typically low PL QY of lead-free manganese halide perovskite-analogues (MHPAs) and provides insight into the fundamental optical properties and phase transformation mechanisms of all-inorganic MHPAs.