CeO6Te2 Nanosheets for Multifunctional Broadband Visible Light Photo Detection and NLO Applications: An Experimental & Computational Approach

Abstract

CeO₆Te₂ (COT) nanosheets were synthesized via a hydrothermal route with systematically varied Ce: Te ratios (1:1, 1:2, 1:3), yielding phase-pure, highly crystalline samples and systematically characterized to correlate their structural, optical, and nonlinear properties. The structural characteristics by XRD, Raman, and XPS analyses confirmed the formation of a layered monoclinic phase with improved crystallinity. Morphological characterization revealed well-formed 2D nanosheets with enhanced crystallinity and atomic ordering at higher Te content. Optical studies by UV–Vis DRS demonstrated progressive bandgap narrowing (1.84–1.67 eV) attributed to Te–O hybridization and lattice modifications. The red-shifting of photoluminescence peaks is caused by Te-induced structural and electronic modifications. Photodetector devices exhibited pronounced and stable photo response, with COT-2 showing the highest photosensitivity (264.5%) and detectivity (1.38 × 10⁷ Jones), while COT-3 displayed maximal photocurrent and nonlinear optical coefficients (|χ⁽³⁾| ≈ 62.6 × 10⁻³ esu). Temporal I-T analysis revealed fast and stable switching, and Z-scan studies confirmed robust third-order nonlinearity dominated by saturable absorption and self-focusing. DFT calculations corroborated the indirect band structure and predicted robust optical activity. These results establish CeO₆Te₂ as a promising multifunctional material for broadband photodetection, optical switching, and nonlinear photonic device applications, with performance tuneable via Ce: Te ratio.