High-Efficiency Ternary Organic Solar Cells with a Good Figure-of-Merit Enabled by Two Low-Cost Donor Polymers

Here, we combine two donor polymers with a relatively short synthesis method and fabricate ternary organic solar cells (OSCs) with a high efficiency and a decent figure-of-merit. A series of characterizations show that the optimal morphology of the ternary blend is the result of the coupling and competition of PTQ10 and PTVT-T, where the molecular packing and phase separation motif of PTQ10 is broken but the strong aggregation of PTVT-T is suppressed, resulting in efficient charge transport and collection, as well as suppressed bimolecular recombination. Moreover, a previously reported solvent-vapor-assisted casting method, taken as an understanding-guided optimization, pushes the optimal system's efficiency to 19.11%. Furthermore, PTVT-T-containing systems clearly show better light soaking and thermal stability than the PTQ10 binary control system, benefiting from the durable polymer matrix. Our work provides a useful approach for developing efficient, stable, and low-cost OSCs based on state-of-the-art donor/acceptor systems through morphology control of the ternary design.