Spin Injection Of Exciton–Polaritons With Halide Perovskites At Room Temperature

ABSTRACT Exciton–polaritons, hybrid photon–exciton quasiparticles, constitute a useful platform for the study of light–matter interaction and nonlinear photonic applications. In this work, we realize a monolithic Tamm–plasmon microcavity embedding a thin film of two‐dimensional halide perovskites with a tunable polymer spacer that controls the exciton–photon detuning. Angle‐resolved optical spectroscopy at room temperature reveals the lower polariton branch dispersions in the linear regime for several detunings. Under circularly polarized, quasi‐resonant laser excitation, the spin injection of excitons and their relaxation toward the lower polariton branch demonstrates its preservation. The observed spin‐polarized emission is consistent with the fast decay of polaritons: spin relaxation mechanisms become inefficient during this short time. Our results provide promising insights into the spin control of polaritonic devices, including chiral lasers and switches.