Cu-Based La and Ce Oxytelluride Nanomaterials for Broadband Visible Light Photoresponse and Nonlinear Optical Applications

Cerium copper oxytelluride (CCOT) and lanthanum copper oxytelluride (LCOT) nanomaterials have been synthesized through a straightforward hydrothermal route to explore their potential applications in broadband photodetection and nonlinear optical (NLO) devices. Structural and morphological studies confirmed the successful synthesis of phase-pure, uniformly dispersed nanostructures. The indirect band gaps observed by UV–vis diffuse reflectance spectra (DRS) at 4.06 and 4.07 eV for CCOT and LCOT, respectively, in the visible range. Defect-assisted recombination was studied using photoluminescence (PL), and it influences charge-carrier dynamics. Measurements of photodetectors were found to have increased photoresponse to an illuminating condition, where LCOT had a higher photosensitivity (12.21) and detectivity (1.54 × 1010 Jones), and CCOT had a high responsivity (1.97 A/W). Temporal I-T experiments verified that switching behavior was stable, repeatable, with fast response and recovery times. Substantial third-order NLO responses with reverse saturable absorption (RSA) and self-focusing behavior were also observed in Z-scan studies, and CCOT exhibited some marginally higher nonlinear susceptibility (χ(3) ≈ 0.535 × 10–6 esu) than CCOT. NLO properties of these materials are supported through the two-photon absorption (2PA) and thermal effects. The synergistic photoresponse and NLO behavior of these Cu-based oxytelluride nanomaterials point to their potential for future optoelectronic, photonic, and optical limiting devices.