Enhanced electrical property of Ni-doped CoO hole transport layer for inverted perovskite solar cells.

Ultrathin Ni doped CoO films were prepared by direct current co-sputtering at room temperature as inorganic hole transport materials for inverted perovskite solar cells. P-type doping was designed to adjust the valence band position of CoO to match the that of CHNHPbI, which would effectively eliminate the interface barrier. Moreover, the hole extraction ability would be enhanced and the power conversion efficiency of the devices hence increased from 3.68% to 9.60%. The optimized performance was also accompanied by decent stability as a result of its intrinsic stability.