Over 18.2%-Efficiency Organic Solar Cells with Exceptional Device Stability Enabled by Bay-Area Benzamide-Functionalized Perylene Diimide Interlayer

A simultaneous further increase in the power conversion efficiency (PCE) and device stability of organic solar cells (OSCs) over the current levels needs to be overcome for their commercial viability. Herein, a bay-area benzamide-functionalized perylene diimide-based electron transport layer, namely H75 is developed, to obtain the aforementioned characteristics. The advantages of H75-employed OSCs include a notable PCE up to 18.26% and outstanding device stabilities under conditions of varying severity (>95% PCE retention after 1500 h upon long-term aging and exceptional T80 lifetimes (the time required to reach 80% of initial performance) of over 1000 h in light-soaking, 500 h in thermal stress at 85 °C, 72 h in 85% high relative humidity, and 100 h in atmospheric-air conditions without encapsulation in conventional architecture). The excellent performance of H75-employed OSC can be attributed to its various beneficial features derived from the bay-area benzamide functionalities (e.g., excellent film-forming ability, suitable energy level, reduced aggregation, and intrinsic high structural stability). The findings of this work provide further insights into the molecular design of electron transport layers  for realizing more efficient and stable OSCs.