Efficient Amplified Spontaneous Emission from Solution-Processed CsPbBr3 Nanocrystal Microcavities under Continuous Wave Excitation

Solution-processed lasers are cost-effective, compatible with a vast range of photonic resonators, and suited for a mass production of flexible, lightweight, and disposable devices. The emerging class of lead halide perovskite nanocrystals (LHP NCs) can serve as a highly suitable active medium for such lasers, owing to their outstanding optical gain properties and the suppressed optical nonradiative recombination losses stemming from their defect-tolerant nature. In this work, CsPbBr3 NCs are embedded within polymeric Bragg reflectors to produce fully solution-processed microcavities. By a systematic parametric optimization of the polymer mirrors, resonators with Q-factors up to 110 can be produced in the green, supporting amplified spontaneous emission (ASE) under continuous wave excitation, with a threshold as low as 140 mW/cm2 . Angle-dependent reflectivity and luminescence studies performed below the ASE threshold demonstrate the strong spectral and angular redistribution of the CsPbBr3 NC spontaneous emission when coupled to the cavity mode. Under resonance, amplification of the output intensity by a factor of 9 in the vicinity of the cavity mode and by a factor of 5 in the whole integrated emission along with an increase of the radiative rate accounted by a Purcell factor of 2 is obtained with respect to NCs deposited in reference microcavity structures.