Effects of Adding PbI2 on the Performance of Hole-Transport Material-Free Mesoscopic Perovskite Solar Cells with Carbon Electrode

Abstract

Perovskite precursor composition is a crucial factor for the performance of perovskite solar cells (PSCs) fabricated by one-step deposition method. In this work, we have investigated the effects of the change of PbI2 concentration in perovskite precursor solutions on the performance of PSCs with mesoporous structure. Hole-transport material-free mesoscopic PSCs with carbon electrode were fabricated by screen printing method and the perovskite precursor solutions were penetrated into mesoporous layers via the top of the carbon layer by one-step deposition method. PSC prepared from the perovskite precursor solution with CH3NH3I, PbI2 and PbCl2 in molar ratio of 4:3:1 achieved the highest device performance, with a short-circuit current density of 22.10 mA cm−2, an open circuit voltage of 0.95 V, a fill factor of 0.64 and the power conversion efficiency of 13.44%. The improved device performance was attributed to the increase of the light absorption ability and a charge recombination resistance in the perovskite layer.