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

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 activelayers. 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.