Laser-Induced Enhancement of Optical Gain and Stability in Potassium-Doped CsPbBr 3 Perovskite Films

In perovskite laser development, it is important to focus on two different regimes of electrical losses: low-power excitation (carrier density lower than 10 18 cm –3 ), when nonradiative processes via trap states can dominate, and high-power excitation (carrier density is 10 18 –10 21 cm –3 ), when Auger recombination prevails. Therefore, passivating the defects that affect radiative recombination is crucial for lowering the lasing threshold and achieving a high optical gain before the Auger onset. Here, we report a combined laser-induced photothermochemical method for the passivation of surface defects by potassium doping in perovskite. This approach yields improved morphology, an optical gain of up to 2600 cm –1, and operational stability under ambient conditions of 35 million laser shots, with only 15% degradation at excitation densities three times above the threshold. The remarkable performance of this laser-induced process will facilitate the development of modern optical applications, including lasing, morphology-controlled photoluminescence yield, and optical information encryption.