One- and Two-Photon Excited Photoluminescence and Suppression of Thermal Quenching of CsSnBr₃ Microsquare and Micropyramid

Thermal photoluminescence (PL) quenching is fundamentally important for perovskite optoelectronic applications. Herein, we investigated PL characteristics of CsSnBr₃ microsquares and micropyramids synthesized by chemical vapor deposition (CVD) and their PL quenching behavior at high temperature. These microstructures have favorable PL performances in ambient atmosphere. Under two-photon excitation, we observed whispering gallery modes (WGMs) in microsquares and amplified spontaneous emission (ASE) in micropyramids. Reversible PL losses due to thermal effect were observed for both samples. Monotonic blue shifts in PL emission upon temperature increase suggest a band gap widening associated with an emphanisis effect. Temperature-dependent spectral line width analysis reveals that a line width broadening is attributed to the dominant electron–longitudinal optical phonon interaction. The estimated activation energy of thermally assisted nonradiative recombination for CsSnBr₃ microsquares and micropyramids is over 310 meV by the Arrhenius equation, which is higher than CsPbBr₃. These results prove that CsSnBr₃ exhibits better thermal stability than Pb-based perovskites.