Cellulose‐Based Oxygen‐Rich Activated Carbon for Printable Mesoscopic Perovskite Solar Cells

Abstract

Carbon electrodes (CEs) are demonstrated as the most stable and cost‐effective back electrodes for perovskite solar cells (PSCs), which influence the performance of related PSCs significantly. Herein, oxygen‐rich activated carbon (AC) is synthesized from the most abundant biomass resource, cellulose, via a feasible carbonization and oxidization process and applied in CEs for hole‐conductor‐free printable mesoscopic PSCs (p‐MPSCs). The obtained cellulose‐based activated carbon (CAC) exhibits a high specific area of 477.14 m2 g−1 and possesses a high oxygen content of 11.9%, promoting the wettability and contact between CEs and perovskites. Moreover, the high oxygen content also leads to an elevated work function of CEs. As a result, p‐MPSCs filled with (5‐AVA)0.03(MA)0.97PbI3 based on CEs containing CAC give an efficiency of 15.5%, whereas those devices based on CEs with no CAC give an efficiency of 13.8%. The improved efficiency benefits from the promoted fill factor and open circuit voltage due to the optimized energy level alignment and enhanced charge extraction by CAC. This work presents a good example for the value‐added utilization of cellulose in the energy conversion systems and offers a feasible strategy for preparing oxygen‐rich CE for PSCs with enhanced performance.