Enhanced Nonlinear Absorption, Refraction, and Optical Limiting Properties of CsPbI₃/TiO₂ Nanocomposites for Innovative Nonlinear Optical Devices

The investigation of nonlinear optical (NLO) properties is crucial for the effective application of CsPbI3/TiO2 nanocomposites in NLO devices. The CsPbI3/TiO2 nanocomposites were synthesized by a hot injection method. Then, the CsPbI3/TiO2 nanocomposites were poured into methyl methacrylate via polymerization to fabricate CsPbI3/TiO2/PMMA organic glasses (OGs). The crystal structure and size morphology of the CsPbI3/TiO2 nanocomposites were examined using X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The nonlinear absorption (NLA), nonlinear refraction (NLR), and optical limiting (OL) properties of the CsPbI3/TiO2/PMMA OGs were investigated by using the Z-scan technique, employing a nanosecond pulse laser operating at a wavelength of 532 nm. The CsPbI3/PMMA and CsPbI3/TiO2/PMMA OGs can be transferred from saturable absorption (SA) to reverse saturable absorption (RSA) by varying the incident energy. In addition, the CsPbI3/TiO2/PMMA OGs exhibit superior NLA, NLR, and OL performances compared to the CsPbI3/PMMA OG and other halide-based perovskites. The enhanced nonlinear optical (NLO) properties of CsPbI3/TiO2/PMMA OGs can be ascribed to the cooperative interaction between CsPbI3 and TiO2. In summary, the results indicate that CsPbI3/TiO2 nanocomposites possess substantial potential for applications in NLO devices such as optical limiters, optical switches, and optical modulators.