Peculiarities of photoinduced heating of perovskite nanocrystals with effective anti-Stokes photoluminescence under near-resonant laser excitation

The optical properties of a photoluminescent material based on CsPbBr$_3$ perovskite nanocrystals were studied in this work. The laser heating of the obtained samples was studied under three different regimes of laser excitation: the photoluminescence band appears in the Stokes region, in the anti-Stokes region, and coincides with the excitation line. It was found that under laser excitation of a certain wavelength, this material is able to demonstrate predominantly anti-Stokes (upconversion) photoluminescence. A method is proposed for estimating the PL quantum yield from data on absorption, photoheating, and the position of the photoluminescence band of a sample at two different wavelengths. The external photoluminescence quantum yield of CsPbBr$_3$ nanocrystals was experimentally determined to be 91 $\pm$ 4%. The results of this work can be useful for the development of optical cooling technology and can be used in the development of laser devices based on perovskite materials.