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

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 m(2) 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)(0.97)PbI3 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.