Optoelectronic multifunctionality of combustion-activated fluorine-doped tin oxide films with high optical transparency

As transparent conducting oxides (TCOs) have been widely used as a common component of many optoelectronic applications, ensuring high conductivity and transparency TCOs has become a pivotal concern. In the present study, we report developing the combustion-activated pyrolysis route of horizontal ultrasonic spray pyrolysis deposition (HUSPD) as a novel strategy to form highly transparent conducting fluorine-doped tin oxide (FTO) films. Compared to the basic route, the combustion-activated FTO films showed an attractive transparent conducting performance (figure of merit of 5.34 × 10 ⁻² Ω ⁻¹ ) with a highly improved optical transparency (90.1%) due to the formation of a smooth and dense film structure to reduce light scattering on the surface, and a decrease of oxygen vacancies to broaden the optical bandgap, all of which yielded an excellent performance as compared to the previously reported studies on the FTO films. Moreover, when the combustion-activated FTO films were used as TCOs of electrochromic devices and dye-sensitized solar cells, they acquired multifunctional effects of (a) an efficient electron transfer by (200) preferred orientations of the FTO; (b) a relaxed light scattering on the interface due to smooth and dense surface morphology of the FTO films; and (c) a broad optical bandgap by decreased oxygen vacancies, resulting in an impressive improvement of both electrochromic and photovoltaic performances. Taken together, our results demonstrate that combustion-activated FTO films are an attractive technique for forming high-performance TCOs that can further be used in multifunctional optoelectronic devices.