Large-area spray deposited Ta-doped SnO2 thin film electrode for DSSC application

Abstract

Large-area (10 × 10 cm2) Ta-doped SnO2 (TTO) thin film was deposited by a facile spray pyrolysis method. The crystallinity, phase purity, and texture properties of the film are studied using XRD analysis. The XPS study confirmed the charge state of Sn to be in 4+, O1s in 2−, and Ta to be in 5+ state. A homogeneous polyhedron morphology was witnessed owing to the Ta dopant effect. The TTO film was highly transparent in the visible to near infrared region (NIR) with an average transmittance value of 81% at 550 nm. The TTO film was having a free carrier concentration of 5.42 × 1021 cm−3 and mobility of 41.7 cm2/Vs. The 4 wt% Ta doped SnO2 electrode exhibits a low sheet resistance of 26 Ω/□ and a high figure of merit value of 6.15 × 10−3 Ω−1. The resistance stability of sheet resistance was fairly good up to 400 °C indicating suitability of the TTO electrode to serve as conducting photoanode/counter electrode in dye-sensitized solar cell (DSSC) device. The DSSC device fabricated with the TTO electrode exhibited appreciable efficiency of 3.26% which is attributed to the enhanced electrical and optical properties by way of doping with Ta element.