An efficient star-shaped fused-ring electron acceptor with C3h-symmetric core via thieno[3,2-b]thiophene extending conjugation strategy,Materials Chemistry Frontiers

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An efficient star-shaped fused-ring electron acceptor with C3h-symmetric core via thieno[3,2-b]thiophene extending conjugation strategy
Materials Chemistry Frontiers ( IF 6.0 ) Pub Date : 2020-09-16 , DOI: 10.1039/d0qm00514b
Weijie Wang _{1,

2,

3,

4,

5} , Tong Wang _{1,

2,

3,

4,

5} , Xiaofu Wu _{1,

2,

3,

4,

5} , Hui Tong _{1,

2,

3,

4,

5} , Lixiang Wang _{1,

2,

3,

4,

5}

Affiliation

The thieno[3,2-b]thiophene (TT) unit is a classic building block to construct high-performance fused-ring electron acceptors (FREAs) for organic solar cells (OSCs). In this work, a star-shaped FREA BTTCTT-ICF based on a new C_3h-symmetric fused-ring core BTTCTT was designed and synthesized by introducing the TT unit to extend the π-conjugation. Due to its strong electron-donating ability and efficient π-electron delocalization, BTTCTT-ICF exhibited a narrow optical bandgap of 1.54 eV and a high absorption extinction coefficient of 3.6 × 10⁵ M⁻¹ cm⁻¹. The blend film of BTTCTT-ICF and the wide bandgap polymer PM6 produced a complementary absorption and a broad EQE spectral range covering 300 to 850 nm. When treated via thermal annealing, the PM6:BTTCTT-ICF blend film exhibited more ordered molecular packing and a suitable phase morphology, which improved its charge mobility and device efficiency. Consequently, the PM6:BTTCTT-ICF-based inverted device achieved the best power conversion efficiency (PCE) of 10.39% with a high short-circuit current density (J_sc) of 16.77 mA cm⁻², open-circuit voltage (V_oc) of 0.91 V and fill factor (FF) of 68.08%. Our results demonstrate that the extension of the star-shaped fused-ring core by TT units is a rational and effective strategy for achieving highly efficient star-shaped FREAs.

中文翻译：

噻吩并[3,2-b]噻吩扩展共轭策略的C3h对称核高效星形稠环电子受体

噻吩并[3,2- b ]噻吩（TT）单元是构建用于有机太阳能电池（OSC）的高性能稠环电子受体（FREA）的经典构件。在这项工作中，通过引入TT单元扩展π共轭，设计并合成了基于新型C _3h对称稠环BTTCTT的星形FREA BTTCTT-ICF。BTTCTT-ICF由于其强大的给电子能力和有效的π电子离域作用，具有1.54 eV的窄光学带隙和3.6×10 ⁵ M ^-1 cm ^-1的高吸收消光系数。BTTCTT-ICF的混合膜宽带隙聚合物PM6产生了互补的吸收和覆盖300至850 nm的宽EQE光谱范围。通过热退火处理时，PM6：BTTCTT-ICF共混膜表现出更有序的分子堆积和合适的相形态，从而改善了其电荷迁移率和器件效率。因此，基于PM6：BTTCTT-ICF的逆变器以16.77 mA cm ^-2的高短路电流密度（J _sc），开路电压（V _oc）获得了10.39％的最佳功率转换效率（PCE）。）为0.91 V，填充系数（FF）为68.08％。我们的结果表明，通过TT单元扩展星形稠密环芯是实现高效星形FREA的一种合理有效的策略。

更新日期：2020-09-30

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