n-Type doping for efficient polymeric electron-transporting layers in perovskite solar cells

n-Type doping of a semi-conducting polymer used as an electron-transporting layer in a perovskite solar cell doubles the performance of the device from 6.5% to 13.93% power-conversion efficiency. This provides a new opportunity for studying various electron transporting polymers in perovskite solar cells. The doped polymer film improves electron extraction from the photoexcited perovskite and the subsequent transport of electrons.