Er3+ and Yb3+ co-doped TiO2−xFx up-conversion luminescence powder as a light scattering layer with enhanced performance in dye sensitized solar cells

Abstract

Er3+ and Yb3+ co-doped TiO2−xFx up-conversion luminescence powder (UC-TiO2−xFx) was fabricated via hydrothermal method and calcined at 500 °C for 2 h. The prepared powders were characterized by SEM, XRD, PL, UC-PL, UV–Vis, SPS and IPCE spectra. The results showed that UC-TiO2−xFx possessed the property of up-conversion, increasing the percentage of visible light that can be absorbed by N719 dyes; it got a lower band gap energy which contributed to a faster electrons injection and decreased the radiative recombination process of photo-generated electrons and holes in TiO2; and adequate F-doping could enhance the performance of luminescence and widened the light absorption in visible light range, but excessive F-doping could cause blue-shift. We applied the UC-TiO2−xFx into dye sensitized solar cell (DSSC), as a light scattering layer for its special morphology, to gain a higher light harvesting and a lower light loss so as to achieve a satisfied DSSC efficiency. Under the simulated solar irradiation of 100 mW cm−2 (AM1.5G), a short-circuit current density of 16.3 mA cm−2, an open-circuit voltage of 0.725 V and an overall energy conversion efficiency of 7.08% were obtained by introducing this light scattering layer.