Double electron transport layers for efficient and stable organic-inorganic hybrid perovskite solar cells

Organic-inorganic hybrid perovskite solar cells (PSCs) have attracted tremendous attention recently because of their excellent photovoltaic performance. High power conversion efficiency (PCE) and long-term stability of PSCs mainly rely on high crystalline quality of perovskite film, good interface contact between functional layers and matching energy level alignment, which can be achieved by crystal growth regulation and interface engineering. Here, we demonstrate a high-performance planar heterojunction PSCs with PCBM/N2200 as double electron transport layers (ETLs). The N2200-based PSCs exhibit an average PCE of 15.50%, which obviously surpass the average PCE of 14.18% of conventional PSCs with only PCBM as ETLs. In comparison with the conventional PSCs, the PCBM/N2200 double ETLs increase built-in potential of devices and decrease interfacial energy barrier of MAPbI(3)/PCBM and then result in higher V-oc. Moreover, non-fullerene material N2200 can efficiently inhibit the aggregation of PC61BM, promote perovskite surface grain growth and passivate perovskite interface defect. All these are beneficial for electron transfer and extraction, and thereby increase the short-circuit current (J(sc)) and the Fill Factor (FF) of N2200 PSCs. In addition, N2200 obviously improve the air- and illumination-stability of PSCs. These results could stem from the interaction between PbI2 as Lewis acid and N2200 as Lewis base. This work indicate that N2200/PC61BM as double ETL is an effective way to get high photovoltaic performance for the inverted planar heterojunction PSCs.