Effect of guanidinium on mesoscopic perovskite solar cells

Hole-conductor-free printable mesoscopic perovskite solar cells based on a TiO2/ZrO2/carbon architecture have attracted much attention due to their low material cost and simple fabrication process. However, the micron-thick mesoporous scaffold always challenges the filling of the perovskite absorber and causes significant charge carrier loss. We employ a multifunctional additive of guanidinium chloride (GuCl) to improve the quality of the CH3NH3PbI3 perovskite absorber, and suppress the recombination reaction in the device. It is found that GuCl effectively enhances the charge carrier lifetimes of the perovskite, and suppresses charge carrier loss in the hole-conductor-free devices. Correspondingly, the open-circuit voltage (VOC) of the device is significantly enhanced from 0.88 V to 1.02 V.