Ultranarrow-band-gap organic semiconductors with fully non-fused conjugated structures display great potential for low-cost organic photoelectric devices. Here, we developed two fully non-fused acceptors, namely, A4T-7 and A4T-12, by introducing different alkoxyl side chains on the π-bridges of the non-fused acceptors. The resulting materials demonstrate ultranarrow optical band gaps of 1.15 and 1.21 eV, respectively. Compared with other ultranarrow-band-gap acceptors constructed with fully fused-ring or partially fused-ring structures, the synthetic complexity of the two acceptors is significantly reduced. Specifically, A4T-7, with symmetric alkoxy chains on the π-bridge, exhibits a more planar molecular configuration compared with A4T-12. Notably, the organic photovoltaic cells based on A4T-7 show a power conversion efficiency of 13.3%. Moreover, cells fabricated with a highly transparent active layer, characterized by an average visible transmittance value of approximately 62.7%, achieve an efficiency of 10.7%. These results represent the highest reported efficiencies for cells utilizing fully non-fused acceptors with ultranarrow band gaps.

具有完全非熔融共轭结构的超窄带隙有机半导体显示出低成本有机光电器件的巨大潜力。在这里，我们通过在非融合受体的π桥上引入不同的烷氧基侧链，开发了两种完全非融合的受体，即A4T-7和A4T-12。所得材料的超窄光学带隙分别为 1.15 和 1.21 eV。与其他全稠环或部分稠环结构构建的超窄带隙受体相比，两种受体的合成复杂度显着降低。具体而言，与 A4T-12 相比，A4T-7 在 π 桥上具有对称烷氧基链，表现出更平面的分子构型。值得注意的是，基于A4T-7的有机光伏电池的功率转换效率为13.3%。此外，采用高度透明的活性层制造的电池，平均可见光透射率约为62.7%，效率达到10.7%。这些结果代表了利用具有超窄带隙的完全非融合受体的细胞的最高报告效率。