Efficient carbon electrode perovskite solar cells with robust buffer interfaces

Carbon electrode perovskite solar cell has great potential in commercial application based on its low cost, superior stability, and facile fabrication process. However, its performance still lags behind that of devices with gold anode, which greatly attributes to the insufficient charge transport and collection at carbon anode side. Herein, efficient anode buffer contact is built by constructing an organic/inorganic composite hole transport bilayer together with strategic carbon precovering/postcovering anode. Adding a charge selective polythiophene (P3HT) layer between perovskite and nickel oxide (NiOx) can reduce charge transfer recombination loss, inhibit moisture infiltration, and crystallographically protect the perovskite underneath from being corroded by carbon paste. Together with a dense and pin-hole free hole transport layer (HTL)/carbon contact through precovering diluted carbon paste, the modified anode buffer interfaces also promote a facilitated charge collection, thus enhancing the photovoltaic performance of low-cost carbon electrode perovskite solar cells to a state-of-the-art value of 20.8% with an enhanced operational stability. This work provides adaptable and robust anode buffer interfaces for efficient, stable and low cost carbon electrode perovskite cells toward commercialization.