To develop wide bandgap donor materials for high performance nonfullerene polymer solar cells (NF PSCs), bis(carboxylate) substituted benzo[1,2-b:4,5-b]dithiophene (BDT) weak electron acceptor (A) unit was used to polymerize with 5-alkylthiophene-2-yl-substituted BDT or 5-alkylthiothiophene-2-yl-substituted BDT donor unit to construct donor-acceptor (D-A) alternative polymers PBDT-BDTC and PBDTS-BDTC, respectively. PBDT-BDTC and PBDTS-BDTC exhibit wide bandgaps over 1.90 eV and low lying highest occupied molecular orbital (HOMO) levels below −5.50 eV. The absorption and energy levels of these two polymers match well with those of the typical low bandgap acceptor ITIC-Th, resulting in a good complementary absorption from 300 to 900 nm and a low HOMO level offset of about 0.15 eV. NF PSCs with an inverted device structure were fabricated and power conversion efficiencies (PCEs) higher than 7% were achieve. Furthermore, PBDT-BDTC based PSCs exhibit much better photovoltaic performance than PBDTS-BDTC based ones after the treatment with 0.5% 1,8-diiodooctane (DIO). The optimized devices gave a PCE of 8.32% with an open-circuit voltage (V_oc) of 0.92 V, a short-circuit current density (J_sc) of 13.91 mA/cm², and a fill factor (FF) of 65.21%, indicating that PBDT-BDTC is a promising polymer donor for NF PSCs. To the best of our knowledge, a PCE of 8.32% is the highest record for bis(carboxylate) substituted BDT based polymers.

为了开发用于高性能非富勒烯聚合物太阳能电池（NF PSC）的宽带隙供体材料，使用了双（羧酸盐）取代的苯并[1,2-b：4,5-b]二噻吩（BDT）弱电子受体（A）单元与5-烷基噻吩-2-基取代的BDT或5-烷基噻吩-2-基取代的BDT供体单元聚合，以分别构建供体-受体（DA）替代聚合物PBDT-BDTC和PBDTS-BDTC。PBDT-BDTC和PBDTS-BDTC表现出超过1.90 eV的宽带隙和低于-5.50 eV的低位最高占据分子轨道（HOMO）水平。这两种聚合物的吸收和能级与典型的低带隙受体ITIC-Th的吸收和能级非常匹配，导致300至900 nm的良好互补吸收和低至约0.15 eV的HOMO能级偏移。制作了具有反向器件结构的NF PSC，并实现了高于7％的功率转换效率（PCE）。此外，PBDT-BDTC基于的PSC表现出比好得多光伏性能PBDTS-BDTC用0.5％1,8-二碘辛烷（DIO）在处理后基于那些。经过优化的器件的PCE为8.32％，开路电压（V _oc）为0.92 V，短路电流密度为（J _sc）为13.91 mA / cm ²，填充因子（FF）为65.21％，表明PBDT-BDTC是有希望的NF PSC聚合物供体。据我们所知，PCE为8.32％，是双（羧酸盐）取代的BDT基聚合物的最高记录。