Plasmonic effect enhancement in dye-sensitized solar cells via Au-decorated Ga-doped TiO₂ photoanodes

Abstract

This study demonstrates a synergistic approach to enhance dye-sensitized solar cell (DSSC) performance through the integration of plasmonic gold nanoparticles (Au NPs) with gallium (Ga³⁺)-doped TiO₂ photoanodes. A series of Au-decorated Ga: TiO₂ (Au/Ga-TiO₂) composites with various gallium nitrate Ga(NO₃)₃ precursor concentrations were synthesized and systematically characterized. FESEM analysis reveals that the sample prepared with 0.50 mM refines the composite morphology, while uniformly dispersed Au NPs (15–20 nm) provide strong localized surface plasmon resonance (LSPR) at 540–560 nm. The champion device achieves a power conversion efficiency (ƞ) of 5.68 ± 0.04% with 0.05 mM Ga(NO₃)₃. This corresponds with high incident photon to current conversion efficiency (IPCE), reaching 64% at 540 nm, lowest charge transfer resistance (R_ct=7 Ω) and longest electron lifetime (τ = 1860 ms). The electrochemical impedance analysis (EIS) and optical characterization analyses confirm that Ga doping improves charge collection, while Au NPs enhance light absorption through scattering effect. This work establishes a coherent strategy for co-engineering electronic and optical properties in hierarchical photoanodes for high-performance photovoltaic devices.