Achieving improved stability and minimal non-radiative recombination loss for over 18% binary organic photovoltaics via versatile interfacial regulation strategy

Interfacial regulation, serving multiple roles, is critical for the fabrication of stable and efficient organic photovoltaics (OPVs). Herein, a multifunctional cathode interlayer PDINO (15 nm) is prepared by regulating film thickness, which is inserted between active components and stable silver electrode to align work function, and maintain good interfacial contact and device stability. The thick film can help to reduce interfacial surface defects, keep stable surface morphology, and block the silver diffusion into the active layer. Consequently, the optimal PM6:Y6 device records an impressive power conversion efficiency (PCE) of 17.48% with minimized non-radiative recombination loss of 0.239 V. More importantly, the unencapsulated device maintains 91% of the original PCE after aging for over 60 days at 25 °C and 10% relative humidity in dark conditions. Meanwhile, the PM6:eC9 device achieves a remarkable PCE of 18.22% with the enhancement of open-circuit voltage (Voc). Furthermore, the 1 cm2 device-based PDINO (15 nm)/Ag shows a high PCE of 15.2% while only 12.6% for PDINO (9 nm)/Al, indicating the good compatibility of PDINO (15 nm) interlayer with the R2R coating processes used in large-area OPVs fabrication. This work highlights the promise of interfacial regulation to simultaneously stabilize and enhance the efficiency of organic photovoltaics.