Effect of Ag/rGO structure formation on LSPR & photoluminescence properties of Ag nanocomposite glasses: Experimental & DFT analysis

This investigation explores the optical and electronic modulation in 73.25TeO₂–20Li₂O–5Bi₂O₃–1Er₂O₃-0.75Ag-xrGO (0–50 mg) glasses with added reduced graphene oxide (rGO), examining the interplay between localized surface plasmon resonance (LSPR) and photoluminescence (PL) enhancement/quenching. The SEM analysis demonstrates the rGO with its characteristic wrinkled and folded morphology, alongside irregularly shaped silver nanoparticles (AgNP) with diameters ranging from 124 nm to 194 nm. The Er³⁺ upconversion PL of both ⁴F_9/2 → ⁴I_15/2 (red) and ⁴S_3/2 → ⁴I_15/2 transition (green) luminescence intensity exhibits a general decrease until a minimum is observed at x = 30 mg. In parallel, the quantum yield ξ and relative intensity enhancement I/I_o of both red and green emission showed a quenching for all glass samples indicated from value of both parameters are not exceeding 1. Employing DFT computational techniques, the electronic structure alterations contributing to PL quenching especially in rGO added glass were computed by comparing between Ag and Ag/rGO hybrid structure deposited in the glass samples. The Ag/rGO system exhibits significant modifications in localized surface plasmon resonance (LSPR) properties due to strong hybridization between Ag d-orbitals and rGO π-orbitals between −4eV and −6eV evident from the broaden d-states and enhanced intensity, may enhanced charge transfer, and changes in the local dielectric environment. These interactions result in a redshift of the LSPR peak, increased UV absorption, and photoluminescence (PL) quenching in the visible range. The unique combination of suppressed radiative modes and enhanced non-radiative energy transfer highlights the potential of Ag/rGO nanocomposite glass for advanced plasmonic applications in sensing, catalysis, and optoelectronics.