Temperature effect of the compact TiO2 layer in planar perovskite solar cells: An interfacial electrical, optical and carrier mobility study

Abstract The power conversion efficiency of TiO 2 based organo-lead halide perovskite solar cells has already surpassed 20% by utilizing low temperature solution processing techniques. However, the electronic structures and exciton/electron transport mechanism at the TiO 2 /perovskite interface are not fully understood. In this report, simple planar TiO 2 /perovskite heterojunctions are fabricated with different TiO 2 compact layers followed by studies of their effect on the charge extraction/transport properties of the deposited heterojunctions. Efficient perovskite solar cells based on these TiO 2 /perovskite heterojunctions [with CH 3 NH 3 PbI 3 and FA 0.81 MA 0.15 Pb(I 0.836 Br 0.15 ) 3 films] have been fabricated and the devices exhibit reproducible efficiency values and good stability. The impact of interfacial potential barrier and TiO 2 surface properties on photogenerated carrier transport mechanisms and overall power conversion efficiency of perovskite solar cells is investigated by using comprehensive electrical and optical characterization methods such as SEM, XRD, XPS, Raman spectroscopy, TRPL, TAS and TPD. Obtained results indicate that efficient device can be fabricated by optimizing of TiO 2 annealing conditions.