Efficient hole-conductor-free, fully printable mesoscopic perovskite solar cells with a broad light harvester NH2CH=NH2Pbl3

Formamidinium lead trihalide perovskite (FAPbl(3)) was successfully introduced into hole-conductor-free, fully printable mesoscopic perovskite solar cells with a carbon counter electrode. With the sequential deposition method, a FAPbl(3) based solar cell yielded an efficiency of 11.9%, superior to the methylammonium lead trihalide perovskite (MAPbl(3)) solar cell efficiency of 11.4%, which is due to broadening of the light, to 840 nm. By optimizing the mixing ratio of the formamidimium and methylammonium cations to 3 : 2, a power conversion efficiency of 12.9% was achieved with this low-cost, fully printable mesoscopic solar cell, which indicated a promising prospect for low-cost photovoltaic technology.