Carbon-Electrode Based Perovskite Solar Cells: Effect of Bulk Engineering and Interface Engineering on the Power Conversion Properties

Carbon electrodes have been adopted widely in perovskite solar cells (PSCs). Due to its suitable work function (though not high enough), the carbon electrode itself could extract photogenerated holes and has helped to achieve a power conversion efficiency of approximate to 16% in the absence of hole-transporting material. Meanwhile, due to the inert chemical nature and the micrometer-sized film thickness (approximate to 10 mu m), carbon electrodes can prolong the stability of PSCs. These merits are appealing for the commercialization of PSCs. However, the efficiency of carbon-electrode PSCs is relatively low. A gap of approximate to 30% remains when comparing with PSCs using evaporated metal films as the electrode. Herein, the progresses in the efficiency of the four kinds of carbon-electrode based PSCs (mesoscopic, embedment, planar, and quasi-planar) are reviewed and compared to metal-electrode based PSCs. Then, the role of bulk engineering and interface engineering in the progress of efficiency is discussed. Finally, outlooks are described in accordance with the discussions.