Photoluminescence and stimulated emission from microcrystalline CsPbCl3 films prepared by amorphous-to-crystalline transformation -: art. no. 205322

Highly excited photoluminescence of CsPbCl3, which is known to be one of the most photoluminescent semiconductors, has been measured for thin films prepared by crystallization from the amorphous phase into microcrystalline/polycrystalline states. With the increase of excitation intensity, the microcrystalline state shows successive jumps of the dominant emission band, from a free-exciton band to its phonon replica and finally to a lowest-energy band originating from exciton-exciton inelastic collision. For the exciton-exciton porcess stimulated emission occurs at very low threshold excitation intensities of the order of 10 kW/cm(2) at 77 K. At higher excitation intensities above 50 kW/cm(2), single-path-light-amplification stimulated emission across the film thickness is observed suggesting a very large optical gain. The large-gain mechanism is attributable to giant oscillator strength effect characteristic of excitonic superradiance recently reported for films prepared in the same way.