DEPOSITION OF OPTICAL THIN FILMS FOR APPLICATIONS IN SOLAR ENERGY CONVERSION DEVICES

Abstract

Considering damaging effect of ultraviolet (UV) radiation on active layers of photovoltaic devices, development of transparent thin film coatings capable of blocking and converting UV photons into visible spectrum have attracted a lot of interest as a strategy for protection of solar cells. Porous Eu-doped TiO₂ thin films prepared using a facile spin coating method exhibited noticeable UV blocking capability. In this work, optical properties of the thin film were enhanced by additional co-doping with yttrium ions, and its effect on photovoltaic performance of dye-sensitized solar cells (DSSCs) was investigated. Photoluminescence measurements demonstrated the increase of absolute quantum yield (QY) of Eu/Y-co-doped TiO₂ thin films up to 31.85% while maintaining the emission pattern with a pronounced peak at 613 nm corresponding to ⁵D₀→⁷F₂ Eu (III) electron transition. Analysis of the solar cell performances before and after application of Eu/Y-co-doped TiO₂ functional film on the illumination side of DSSCs revealed the increase in photocurrent and power conversion efficiency up to 30.3% and 28.9%, respectively, due to supplying of additional photons in the red region. Thus, preliminary data proved that downconverted red photons can be partially reabsorbed by DSSCs leading to a power output improvement.