Encapsulation of CsPbBr 3 quantum dots in silica matrices and study of enhanced nonlinear optical properties

Abstract All-inorganic cesium lead halide perovskite quantum dots (PQDs), CsPbX3 (X=Cl, Br, I), exhibit exceptional potential in nonlinear optical (NLO) applications. This is due to their outstanding optoelectronic properties, including high photoluminescence quantum yield (PLQY), tunable band gaps, and strong absorption coefficients. However, their practical utility is severely limited by their environmental instability against ambient air and moisture. In this study, CsPbBr3 QDs were encapsulated in a SiO2 matrix using a sol-gel method to fabricate CsPbBr3/SiO2 gel-glass composites. Structural characterization(TEM, XRD, and FT-IR) confirmed the uniform dispersion and complete encapsulation of the QDs within the amorphous SiO2 network. Optical analyses revealed that the composites retained the intrinsic absorption and emission characteristics of the CsPbBr3 QDs (bandgap: 2.29 eV; fluorescence peak: 510 nm), while exhibiting tunable linear transmittance (50%-82%). Z-scan measurements under 532 nm picosecond pulsed laser excitation revealed significant nonlinear absorption coefficients (β) of up to 0.85 cm/GW and a low optical limiting threshold (OL) of 0.22 J/cm2. Importantly, SiO2 encapsulation markedly enhanced the environmental stability of the CsPbBr3 QDs, and their NLO properties remained stable after 365 days of storage under ambient air conditions. This work provides a viable strategy for realizing halide perovskite-based optical limiting devices and establishes a promising platform for further development. Future device-level integration and cycling tests will be essential for practical deployment.