Cost effective perovskite solar cells with a high efficiency and open-circuit voltage based on a perovskite-friendly carbon electrode

For low-temperature paintable carbon based perovskite solar cells (PSCs), the commercial carbon paste utilized to prepare carbon electrodes damages the well-fabricated perovskite films, resulting in bad photoelectric properties. Herein, we have successfully prepared a low temperature perovskite-friendly and environmentally benign carbon paste using propylene glycol monomethyl ether acetate as a solvent, which has shown a high electrical conductivity. More importantly, with the exclusive carbon paste, the perovskite film keeps a dense and uniform morphology. The as-developed PSCs do not involve the fabrication of organic hole transport materials (HTMs) which are generally expensive and air-sensitive, greatly limiting the long-term stability. The cost-effective HTM-free carbon-based PSCs demonstrate a champion power conversion efficiency of up to 13.5% and a champion open-circuit voltage of up to 1.07 V with an active area of 0.1 cm², the highest value reported so far for carbon-based PSCs with MAPbI₃ as the light harvester. Furthermore, a long-time stability test shows that the solar cells with the as-prepared carbon electrode retain more than 90% of their initial power conversion efficiency after 960 h.