Interface optimization of hole-conductor free perovskite solar cells using porous carbon materials derived from biomass soybean dregs as a cathode

Hole transporting material (HTM)-free carbon-based perovskite solar cells (C–PSCs) have attracted widespread attention for their notable characteristics of excellent long-term stability and low cost. However, the power conversion efficiency (PCE) of C–PSCs is significantly lower than that of HTM-based PSCs. This is mostly due to the unexpected electron recombination happening at the interface of perovskite/carbon. In this study, biomass-based carbon materials were obtained from discarded soybean dregs with sufficient pore size and good conductivity through programmed temperature carbonization and KOH activation processes. Composites of KOH-activated soybean dregs carbon and conductive carbon were used as the counter electrodes (CEs) of C–PSCs, the electrode interface performance was significantly improved and a PCE of 12.05% was obtained, which was 50% higher than that of pure carbon-based C–PSCs. Through long-term stability tests, it was found that the efficiency of the unpackaged cell did not decrease in after 960 h in the air.