Abstract Four new conjugated polymers based on benzodithiophene, thiophene and 2,1,3-benzothiadiazole or 5,6-difluoro-2,1,3-benzothiadiazole were synthesized and investigated as absorber materials for organic photovoltaics. The effect of (bi)thiophene π-spacers and fluorine substitution on the physicochemical and optoelectronic properties of the polymers was revealed and correlations were drawn with their electrical characteristics in organic solar cells. In particular, introducing either thiophene spacers or fluorine substituents does not affect much the photovoltaic performance of the polymers, while the combination of both routes was found to be a promising strategy for improving the charge carrier mobilities and morphology of the polymer-fullerene blends as well as light power conversion efficiency in solar cells based on these materials. The bulk heterojunction organic solar cells based on the π-bridged and fluorinated polymer P4 showed the highest short-circuit current density and power conversion efficiency of 7 %, which is an inspiring value for fullerene-based organic photovoltaics. Most importantly, our findings provide important insights into rational design of high-performance conjugated polymers while pursuing a combination of two efficient backbone functionalization strategies based on introduction of fluorine substituents and π-spacers to control the geometry and electronic characteristics of the polymer chains.

中文翻译：

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π-间隔基和氟负载对(X-DADAD)n苯并二噻吩基共轭聚合物光电和光伏性能的影响

摘要 合成了四种基于苯并二噻吩、噻吩和2,1,3-苯并噻二唑或5,6-二氟-2,1,3-苯并噻二唑的新型共轭聚合物作为有机光伏吸收材料。揭示了（双）噻吩π-间隔基和氟取代对聚合物物理化学和光电特性的影响，并绘制了它们在有机太阳能电池中的电特性的相关性。特别是，引入噻吩间隔基或氟取代基不会对聚合物的光伏性能产生太大影响，而两种途径的结合被发现是改善聚合物 - 富勒烯共混物的电荷载流子迁移率和形态的有前途的策略作为基于这些材料的太阳能电池的光功率转换效率。基于 π 桥接和氟化聚合物 P4 的本体异质结有机太阳能电池显示出最高的短路电流密度和 7% 的功率转换效率，这对于基于富勒烯的有机光伏来说是一个鼓舞人心的价值。最重要的是，我们的发现为高性能共轭聚合物的合理设计提供了重要的见解，同时追求基于引入氟取代基和 π-间隔基的两种有效主链功能化策略的组合，以控制聚合物链的几何形状和电子特性。