Five-membered aromatic heterocycles are widely used for constructing conjugated polymers in the application of organic photovoltaic cells (OSCs). In this work, three polymers containing furan, thiophene, and selenophene as the π-bridge in their backbones, namely PBDB-TF-O, PBDB-TF-S and PBDB-TF-Se, were designed, synthesized and characterized. By blending with BTP-4Cl, an emerging non-fullerene acceptor, the OSC devices based on the three polymer donors show distinct photovoltaic properties with the variation of the five-membered chalcogen-π-heterocycles. It is demonstrated that PBDB-TF-O tends to undergo severe aggregation while blending with the NFA molecule due to its strong polarity by the introduction of oxygen atoms, and the heavy atom effect of Se exists in PBDB-TF-Se, resulting in its poor luminescence property and larger non-radiative energy loss. The PCE is 0.55% and 11.92% for PBDB-TF-O and PBDB-TF-Se based OSCs, respectively. PBDB-TF-S, the polymer containing thiophene as the heterocycle-π-bridge, presents appropriate aggregation characteristics, decreased non-radiative energy loss, and high and balanced mobilities, and thus presents a desirable PCE of 16.22%. This work indicates that thiophene should be the most appropriate unit among the three chalcogen-heterocycles to construct the backbones of conjugated polymers with high photovoltaic performance.

中文翻译：

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对五元硫属元素-π-杂环桥共聚物的光伏性能的影响

五元芳香族杂环广泛用于构建有机光伏电池（OSC）应用中的共轭聚合物。在这项工作中，设计，合成和表征了三种在其主链中包含呋喃，噻吩和硒烯作为π桥的聚合物，即PBDB-TF-O，PBDB-TF-S和PBDB-TF-Se。通过与新兴的非富勒烯受体BTP-4Cl混合，基于三种聚合物供体的OSC器件显示出独特的光伏特性，并带有五元硫属元素-π-杂环。结果表明，PBDB-TF-O极性强，通过引入氧原子而与NFA分子共混时，倾向于发生严重的聚集，并且PBDB-TF-Se中存在Se的重原子效应，导致其发光性能差和更大的非辐射能量损失。基于PBDB-TF-O和PBDB-TF-Se的OSC的PCE分别为0.55％和11.92％。含有噻吩作为杂环-π-桥的聚合物PBDB-TF-S具有适当的聚集特性，降低的非辐射能量损失以及较高且平衡的迁移率，因此具有理想的PCE 16.22％。这项工作表明，噻吩应该是三个硫属元素杂环中最合适的单元，以构建具有高光伏性能的共轭聚合物的主链。以及高且平衡的迁移率，因此呈现出理想的PCE为16.22％。这项工作表明，噻吩应该是三个硫属元素杂环中最合适的单元，以构建具有高光伏性能的共轭聚合物的主链。以及高且平衡的迁移率，因此呈现出理想的PCE为16.22％。这项工作表明，噻吩应该是三个硫属元素杂环中最合适的单元，以构建具有高光伏性能的共轭聚合物的主链。