Photodegradation of mixed organic dyes using Nb and W co-doped spray coated transparent conducting SnO₂ thin films

The implications of niobium (Nb) and tungsten (W) co-dopants on the physicochemical characteristics of spray deposited tin oxide (SnO₂) thin films are investigated in order to evaluate it as an alternative transparent conducting oxide electrode. Co-doping with two cationic elements enables tweaking of the morphological and optoelectronic properties of SnO₂ in thin film form. Spray pyrolysis is utilized for obtaining Nb (1 and 2 wt%) and W (fixed 4 wt%) co-doped SnO₂ thin films on glass substrates. The surface wettability test shows that the cationic co-dopants W and Nb have influenced the SnO₂ thin film by altering the surface features thereby reducing the contact angle value. The transmittance spectra indicate that pure SnO₂ has a higher transmittance value of 83%, which diminishes upon addition of the W dopant and increases after Nb is introduced as a co-dopant. The linear four-probe measurement revealed that the films have a uniform sheet resistance around the centre with a low sheet resistance of ∼62 Ω □^-1. The stabilized transparent conducting electrode's figures of merit of the deposited W and Nb co-doped SnO₂ thin films are calculated and the promising results of photocatalytic tests for mixed dyes are discussed in correlation with the physicochemical and optoelectronic properties.