Fluorine-Doped Tin Oxide Thin Films with High Surface Conductance and Low Transparency for Boosting Performance in Dye-Sensitized Solar Cell Applications

Transparent conductive oxide films, like fluorine-dopedtin oxide(FTO), are needed for electrochemical devices. FTO films are attractivedue to their cost-effectiveness and high-temperature tolerance. Generally,solar cell fabrication requires high transmittance and low-conductivityFTOs. However, achieving both simultaneously poses a fundamental challenge.This study investigates the impact of FTO layer thickness, sheet resistance,transparency, and film morphology on optimizing the performance ofdye-sensitized solar cells. To achieve this, a precursor solutioncontaining SnCl4 & BULL;5H(2)O and NH4F in isopropanol is sprayed onto a soda-lime glass substrate at 500 & DEG;C to form FTO films. The film thickness is varied by repeatingthe spray cycles. By increasing the number of spray cycles, the sheetresistance of the FTO film improves to & SIM;1.20 & omega; (-1) with the expense of transmittance. The achieved verylow sheet resistance of & SIM;1 & omega; (-1) (& SIM;3.54 x 10(-4)) & omega; cm resistivityfor the FTO film confirms the promise of this sequential spray pyrolysistechnique in preparing highly conductive inert electrodes for variousapplications. Furthermore, DSCs with low transparency and sheet resistanceshowed higher-energy conversion efficiencies, challenging the currentprerequisite of the requirement of high transmittance. The best efficiency(5.14%) is achieved with FTO films having a 34.2% transmittance anda 3.27 & omega; (-1) sheet resistance, outperformingstandard FTO films (4.74%) with a 10 & omega; (-1) sheet resistance and an & SIM;83% transmittance. The results indicatethat the transparency of FTO is not a dominant factor and carefullycontrolled light scattering and electrical properties in translucentFTO films would lead to the realization of dye-sensitized solar cellsthat deliver superior efficiency.