Down-conversion Ce-doped TiO2 nanorod arrays and commercial available carbon based perovskite solar cells: Improved performance and UV photostability

Ce-doped TiO 2 nanorod arrays as the mesoporous supporting layer and TiO 2 compacted electron blocking layer was simultaneously fabricated by one-pot hydrothermal method . Ce-doped TiO 2 nanorod was utilized as down-conversion luminescence centers and commercial available carbon was used in hole-transport-free perovskite solar cells . SEM indicated that the doping of Ce reduced the diameter of TiO 2 nanorods. XRD and EDS spectra demonstrate the successful incorporation of Ce ions. UV–Vis absorption spectra and PL emission spectra show that the down-conversion center Ce 4+ can effectively utilize ultraviolet light and extend the absorption into the ultraviolet region. The carbon-based device using the optimized Ce doping concentration achieved power conversion efficiency (PCE) of 10.1%, which was 24.6% higher than that of undoped device. Ce doping changes the band gap of TiO 2 and the Fermi energy level, and thus improve the open circuit voltage. The open circuit voltage decay curve show that Ce-doped TiO 2 prolongs electron lifetime . EIS analysis hints that more carriers are generated. The UV stability has also been significantly improved., PCE of the optimized Ce-doped device still retains 90% of the initial value , however, the undoped device decreases to 55% of the initial value under light irradiation at ambient atmosphere for 12 h.