UV LIGHT BLOCKING AND CONVERSION BY POROUS EUROPIUM-DOPED TITANIUM DIOXIDE (TIO2-EU) THIN FILMS FOR POTENTIAL PROTECTION OF PHOTOVOLTAIC DEVICES

In recent years, transparent thin films capable of screening and converting ultraviolet (UV) photons into visible spectrum gained significant interest in the protection of photovoltaic devices.We investigated the optical properties and UV screening capability of europium-doped titanium oxide (TiO2 Eu) thin films deposited by the spin-coating method from a solution precursor for the first time in this study. We showed that TiO2-Eu thin films demonstrate europium concentration-dependent optical properties, and the quantum yield of the optimized sample was found to be ~10.2%. Transmittance and photoluminescence measurements suggested that TiO2 Eu thin film can effectively block UV photons (~30.5% at 320 nm) at glass substrate and convert them to the red emission thanks to 5D0/7Fj (j ¼ 0, 1, 2, 3, and 4) Eu (III) electronic transitions. Photodegradation experiments with methylene blue dye revealed that TiO2 Eu thin films offer better UV protection compared to uncoated samples. We strongly believe that porous TiO2 Eu thin films can be effectively utilized as a UV blocking and light conversion coating