Amplified spontaneous deep-blue emission in sub-millimeter sized CsPbCl3 crystals

Inorganic perovskite CsPbX3 (X = Cl, Br, I) has shown considerable potential as a laser medium based on its excellent luminescence properties. However, the wide bandgap and high defect density of chloride-based perovskite result in its poor radiative efficiency and severe non-radiative losses, which impede the development of deep-blue lasers. In this work, we successfully demonstrate the amplified spontaneous emission (ASE) in sub-millimeter sized CsPbCl3 crystals. The nonlinear ASE peak is located at 414 nm with a low threshold of 27.1 μJ/cm2 at 50 K under one-photon excitation. Through a series of temperature-dependent and power-dependent photoluminescence spectroscopic analyses, the carrier recombination dynamics and optical gain mechanisms were further elucidated. The CsPbCl3 perovskite laser medium demonstrates a characteristic temperature of 70 K and an ASE behavior up to 130 K under one-photon excitation. Additionally, two-photon excitation was also demonstrated with a higher characteristic temperature of 82 K and an ASE action even up to 280 K. These findings clarify the potential of the emerging inorganic perovskite CsPbCl3 crystal as an excellent medium for a crystal laser in the deep-blue region.