Doped Charge‐Transporting Layers in Planar Perovskite Solar Cells

Organometal halide perovskite solar cells (PSCs) are brought to the forefront of research focus in photovoltaics field with a rapid efficiency rising over 22% in the past few years. Interface engineering with suitable hole‐transporting layer (HTL) and/or electron‐transporting layer (ETL) plays very important roles in controlling the charge carrier behavior in planar PSCs. Particularly, the utilization of doped charge‐transporting layers is regarded as an efficient route to further improve the device performance of the planar PSCs. In this review, first the fundamental roles of doped charge‐transporting layers are briefly introduced. Then, the review mainly summarizes the recent progress in the development of doped HTLs and ETLs. Finally, a prospective of promising applications of doped charge‐transporting layers in planar PSCs is proposed.