Yttrium-doped TiO2 nanorod arrays and application in perovskite solar cells for enhanced photocurrent density

Crystalline yttrium-doped rutile TiO2 nanorod arrays were synthesized and successfully implemented as a photoanode of perovskite solar cells. Study shows that yttrium was successfully doped and TiO2 band gap changes from 3.07 eV to 3.02 eV. A positive shift of 100 mV in the flat-band potential (Vfb) was observed in Y-doped rutile TiO2 nanorods. A power conversion efficiency of 7.95% and a photocurrent density of 15.13 mA/cm2 were obtained for the doped sample. The photocurrent density is 1.47 times higher than that of the un-doped device. Incident photon-to-current conversion efficiency shows Y-doped device has a clear increase in quantum efficiency in the visible light range from 450 and 750 nm. Open circuit voltage decay measurements demonstrate the superior ability of Y-doped TiO2 nanorod for separating electrons and holes and decreasing the recombination events. The improved performance is possibly attributed to the enhanced electron injection and transfer efficiency caused by a positive shift in Vfb and a reduction in charge recombination. This study opens a door toward the improvement of photocurrent density of perovskite solar cell via an element doping route.