Three metal‐free organic D−π−A dyes with benzothieno[3,2‐b]indole as electron donor, cyanoacrylic acid as both electron acceptor and anchoring group with benzene (BID‐1), thiophene (BID‐2) and furan (BID‐3) as π‐spacers were designed and synthesized for application in dye‐sensitized solar cells (DSSCs). A planar and electron‐rich heterocycle such as benzothieno[3,2‐b]indole offers better backbone rigidity and improves charge transport properties in comparison to indolo[3,2‐b]indole donor, previously reported from our group. Additionally, we synthesized a benzothieno[3,2‐b]indole donor grafted with longer alkyl chains which efficiently prevented the approach of oxidized species in the electrolyte coming closer to semiconductor thereby arresting recombination. A power conversion efficiency of 4.11 % was achieved for dye‐sensitized solar cells based on the furan π‐spacer benzothieno[3,2‐b]indole dye BID‐3 in comparison to the corresponding indolo[3,2‐b]indole dye (IID‐3) having an efficiency of 1.71 %. Detailed interfacial electrical measurements along with theoretical calculations disclosed the mechanism of back electron transfer and improvement in photovoltaic performance with respect to variation in both donor and π‐spacer.

中文翻译：

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通过基于苯并噻吩并[3,2-b]吲哚的染料敏化太阳能电池中的供体和π-间隔变化调节反电子传递。

三个无金属有机d-π-A染料与苯并噻吩并[3,2-b]吲哚作为电子供体，氰基丙烯酸既是电子受体和锚固基团用苯（BID - 1），噻吩（BID - 2）和呋喃（出价‐ 3）设计并合成了π垫片，用于染料敏化太阳能电池（DSSC）。与以前从我们小组报道的吲哚[3,2-b]吲哚供体相比，诸如苯并噻吩并[3,2-b]吲哚等平面且富含电子的杂环具有更好的骨架刚度，并改善了电荷传输性质。此外，我们合成了接枝有较长烷基链的苯并噻吩并[3,2-b]吲哚供体，有效地阻止了电解质中氧化物质接近半导体的途径，从而阻止了重组。与相应的吲哚[3,2-b]吲哚染料相比，基于呋喃π-间隔基苯并噻吩并[3,2-b]吲哚染料BID - 3的染料敏化太阳能电池的功率转换效率为4.11％（IID‐ 3）的效率为1.71％。详细的界面电学测量以及理论计算揭示了相对于供体和π-间隔物变化的逆电子转移机理和光伏性能的改善。