Simultaneously Enhancing Efficiency and Stability of Ternary Organic Solar Cells via a...

The ternary strategy has emerged as an effective approach to enhance the photovoltaic performance of organic solar cells (OSCs), yet simultaneously improving both efficiency and stability remains a formidable challenge. Herein, we report a small-molecule donor (TiC12), featuring a thieno[3,2-c]isochromene unit, as a third component to fabricate ternary fullerene-based OSCs using the low-cost PTB7-Th:PC₇₁BM host matrix. The influence of TiC12 on the active-layer morphology, device efficiency, and long-term stability is systematically investigated. The results reveal that the incorporation of TiC12 enables precise regulation of the blend film morphology, leading to a marked improvement in photovoltaic performance. Consequently, the optimized ternary devices achieve a notable power conversion efficiency (PCE) of 10.42%, which significantly surpasses that of the corresponding binary PTB7-Th:PC₇₁BM counterparts (9.16%). More importantly, the ternary system simultaneously exhibits substantially enhanced operational stability, retaining 82.7% of its initial PCE after 2304 h under ambient storage in a N₂-filled glovebox. This work demonstrates that TiC12, with its unique thieno[3,2-c]isochromene framework, represents a promising third-component candidate for achieving both high efficiency and superior stability in ternary fullerene OSCs.