Green‐Solvent‐Processed High‐Performance Ternary Organic Solar Cells Comprising a Highly Soluble and Fluorescent Third Component

Abstract Nowadays, it is still a great challenge to obtain high‐performance green‐solvent‐processed organic solar cells (OSCs). In this study, a ternary blend strategy (one donor and two acceptors, 1D/2A) is developed to solve the difficulty of film morphology modulation during the fabrication of high‐performance green‐solvent‐processed OSCs. A typical high‐performance halogenated‐solvent processable binary system D18:BTP‐eC9‐4F is selected as the host, its green‐solvents‐processed devices show an inferior power conversion efficiency (PCE) of ≈16%. SM16 with two 3D shape persistent end groups is selected as the third component due to its high fluorescence quantum yield, reduced intermolecular interaction, good solubility, and moderate crystallinity. As a result, the ternary devices display bicontinuous interpenetrating networks, reduced energy loss, and suppressed charge carrier recombination losses. Hence, an excellent PCE of 18.20% is achieved for the D18:BTP‐eC9‐4F:SM16 ternary devices, which is much higher than D18:BTP‐eC9‐4F‐based binary ones and also one of the highest PCEs for the green‐solvents‐processed OSCs. Besides, this strategy also demonstrates a good universality for other binary systems and becomes an effective pathway for the development of green‐solvent processable high‐performance OSCs.