Enhanced Charge Collection in Non‐Fullerene Organic Solar Cells Using Iridium Complex as an Electron Extraction Layer

Abstract Ultrathin iridium (Ir) complexes (e.g., bis[2‐(4,6‐difluorophenyl)pyridinato‐C2,N](picolinato)iridium(III) (FIrpic)) are first introduced as electron extraction layers (EELs) in non‐fullerene organic photovoltaics (OPVs), and a set of devices based on non‐fullerene materials is fabricated. It is demonstrated that this approach can rationally enhance the corresponding short current density and open circuit voltage and finally improve the photovoltaic performance of OPVs. Furthermore, optimized bilayer EELs using combined FIrpic and 8‐hydroxyquinoline lithium (Liq) are investigated. The resulting device presents excellent power conversion efficiency (PCE) of 15.85%, which is much higher than that of control device without FIrpic layer (14.6%). Moreover, Ir complexes show great universality when combined with other materials serving as EELs. This may provide an extra direction for further enhancement of OPVs performance.