Over 17.7% efficiency ternary-blend organic solar cells with low energy-loss and good thickness-tolerance

Abstract

Ternary-blend organic solar cells (TOSCs) are fabricated with PM6:BTP-4F-12 as the host system and IT-M as the third component. The third component IT-M takes multiple roles in improving performance of TOSCs through reducing energy-loss of the optimized TOSCs, optimizing molecular arrangement and phase separation in active-layers. The well optimized molecular arrangement and phase separation can be beneficial to charge separation and transport in TOSC, which can be confirmed by the characterization of 2D grazing incidence wide-angle X-ray scattering, transmission electron microscopy, magneto-photocurrent, as well as electrochemical impedance spectroscopy. By finely optimizing IT-M content, a power-conversion-efficiency (PCE) of 17.71% is achieved in the optimized TOSCs, benefiting from simultaneously enhanced short-circuit-current density (JSC) of 25.95 mA cm−2, open-circuit-voltage (VOC) of 0.875 V and fill-factor (FF) of 78.02% in comparison with the OSCs with PM6:BTP-4F-12 as active-layers. Furthermore, average PCE over 15% can be achieved from twenty individual TOSCs with active-layer thickness of 300 nm, indicating the optimized TOSCs have excellent thickness tolerance.