Sprayed and mechanical-modified graphite layer as transferred electrode for high-efficiency perovskite solar cells

As an alternative of evaporated metal top electrode in perovskite solar cells, the transferred top electrode technique has the outstanding advantage of simple process. And in the case of carbon based transferred top electrode, the efficiency of corresponding perovskite devices can be higher than 20%. During the solid-to-solid electrode transferring process, it is essential to achieve effective contact and to avoid damage of bottom functional layers for an improved device performance. In this work, a sprayed graphite layer on conductive substrate is employed as transferred top electrode for perovskite solar cells. A simple mechanical polishing treatment is further adopted to modify the surface status of graphite layer. Compared with as sprayed graphite electrode, polished electrode shows better electrical property and optimized interface contact with hole-transporting layer. Thus, the average efficiency of perovskite device with mechanical modified electrode can significantly increase from 16.3% to 19.2%.