Superfluorescence in single-crystal quasi two-dimensional lead halide perovskites

Superfluorescence (SF) is a collective spontaneous emission process arising from the coherent coupling of many quantum emitters excited by the same optical field. Although SF is typically observed only at cryogenic temperatures (below 78 K), recent studies have revealed its emergence at room temperature in quasi-two-dimensional (2D) metal halide perovskites. Motivated by the hypothesis that the superlattice ordering within quasi-2D structures facilitates room-temperature SF, we investigate single-crystal microplatelets of quasi-2D perovskites (PEA)₂​PbX₄​ (X = Br, I) using steady-state and Kerr-gated time-resolved spectroscopies. Distinct signatures of SF are observed, including delayed pulsed emission, a quadratic dependence of emission intensity on excitation power, and Burnham–Chiao ringing near the excitation threshold.