Vertical Cavity Biexciton Lasing in 2D Dodecylammonium Lead Iodide Perovskites

Layered Ruddlesden‐Popper‐type (2D) metal‐halide perovskites exhibit markedly increased exciton binding energies, exceeding 150 meV, compared to their 3D counterparts. Many‐body physics, enabled by Coulomb interactions, plays a strong role and raises the biexciton binding energy to 50 meV. Here, photoluminescence at a range of temperatures and carrier concentrations in thin films of the layered perovskite material (C12H25NH3)2PbI4 is reported. Biexcitons are directly observed up to a sample temperature of 225 K. An optical microcavity (comprising a distributed Bragg reflector and a metal mirror), with photonic resonances tuned near to the biexciton energy, is constructed. Optically‐pumped biexciton lasing up to 125 K, with a threshold peak excitation density of 5.6 × 1018 cm−3, is observed. The demonstration of biexciton lasing above liquid nitrogen temperatures is a crucial step for the application of layered perovskites in photonic applications.