New wide-bandgap donor-acceptor-π type conjugated polymers, PBTTT and PBTDTT, containing different π-extended conjugated bridges between benzodithiophene (BDT) as a donating unit and 3-carboxylthiophene (3CT) as a weak electron-withdrawing group, were successfully synthesized and employed as donor polymers for polymer solar cells. Thienothiophene (TT) and dithienothiophene (DTT) were selected as fused thiophene bridges for inclusion in the polymer backbone instead of a single thiophene. As a control donor polymer, PBTT containing a single thiophene bridge was also prepared. Its properties were compared with those of PBTTT and PBTDTT. As the conjugation length of the p-extended bridge (i.e., from thiophene to DTT) increased, the bandgap of the polymer slightly decreased, and the highest occupied molecular orbital level shifted to a higher-lying level. Compared to PBTT, PBTTT and PBTDTT exhibited relatively low solubility and red-shifted absorption spectra in solution states. PBTTT and PBTDTT showed strong aggregation between polymer chains, even in solution states, which were similar to the film state. Among the three copolymers, PBTTT-based non-fullerene polymer solar cells (NF-PSCs) with ITIC-Me showed a high power conversion efficiency of 7.30% with a high short circuit current density of 14.05 mA/cm². The superior performance of the NF-PSCs based on PBTTT may be attributed to their predominant face-on orientation of polymer chains and relatively more favorable surface morphology.

新的宽带隙供体-受体-π型共轭聚合物，PBTTT和PBTDTT，在苯并二噻吩（BDT）作为供体单元和3-羧基噻吩（3CT）作为弱吸电子基团之间含有不同的π-扩展共轭桥。合成并用作聚合物太阳能电池的供体聚合物。噻吩并噻吩 (TT) 和二噻吩并噻吩 (DTT) 被选为稠合噻吩桥，用于包含在聚合物主链中，而不是单一的噻吩。作为对照供体聚合物，还制备了含有单个噻吩桥的 PBTT。将其性能与 PBTTT 和 PBTDTT 的性能进行了比较。作为 p 延伸桥的共轭长度（即, 从噻吩到 DTT) 增加, 聚合物的带隙略有减小, 最高占据分子轨道水平转移到更高的水平。与 PBTT 相比，PBTTT 和 PBTDTT 在溶液状态下表现出相对较低的溶解度和红移吸收光谱。PBTTT 和 PBTDTT 在聚合物链之间表现出强烈的聚集，即使在溶液状态，这与薄膜状态相似。在这三种共聚物中，具有 ITIC-Me 的 PBTTT 基非富勒烯聚合物太阳能电池 (NF-PSC) 显示出 7.30% 的高功率转换效率和 14.05 mA/cm ²的高短路电流密度。基于 PBTTT 的 NF-PSC 的优异性能可能归因于它们主要的聚合物链正面取向和相对更有利的表面形态。