“Ternary polymer solar cells (PSCs) are one of the most promising device architectures that maintains the simplicity of single-junction devices and provides an important platform to better tailor the multiple performance parameters of PSCs. Herein, a ternary PSC system is reported employing a wide bandgap polymeric donor (PBTA-PS) and two small molecular nonfullerene acceptors (labeled as LA1 and 6TIC). LA1 and 6TIC keep not only well matched absorption profiles but also the rational crystallization properties. As a result, the optimal ternary PSC delivers a state of the art power conversion efficiency (PCE) of 14.24%, over 40% higher than the two binary devices, resulting from the prominently increased short-circuit current density (Jsc) of 22.33 mA cm⁻², moderate open-circuit voltage (Voc) of 0.84 V, and a superior fill factor approaching 76%. Notably, the outstanding PCE of the ternary PSC ranks one of the best among the reported ternary solar cells. The greatly improved performance of ternary PSCs mainly derives from combining the complementary properties such as absorption and crystallinity. This work highlights the great importance of the rational design of matched acceptors toward highly efficient ternary PSCs.”

三元聚合物太阳能电池（PSCs）是最有前途的器件之一。2019年中国科学院青岛生物能源与过程研究所阳仁强课题组报道了一种三元聚合物太阳能电池PSCs体系，由宽带隙聚合物供体（PBTA-PS）和两个小分子非富勒烯受体（简称为LA1和6TIC）组成。其中两个小分子非富勒烯受体LA1和6TIC不仅具有良好的吸收曲线，还有合理的结晶性能。这样三元组合的PSCs最大的转换效率（PCE）为14.24%，比一般的两组分电池器件PCE高出40%以上，J_sc显著增加到22.33 mA cm⁻²，开路电压（V_oc）为0.84 V，且填充系数FF接近76%。该文章”Ternary Polymer Solar Cells with High Efficiency of 14.24% by Integrating Two Well-Complementary Nonfullerene Acceptors”[1] 发表在ADVANCED  FUNCTIONAL MATERIALS上。引入两个小分子受体LA1和6TIC的PSCs以其优异的PCE性能在已报道的三元太阳能电池中名列前茅。

Figure 1. a) Chemical structures of PBTA-PS, LA1, and 6TIC. b) Normalized absorption spectra of neat PBTA-PS, LA1, 6TIC films and normalized photoluminescence (PL) emission spectrum of neat LA1 film. c) Energy level diagrams of PBTA-PS, LA1, and 6TIC.

“Series of binary and ternary PSCs were fabricated by using PBTA-PS as donor and LA1 and 6TIC as acceptors. The LA1- and 6TIC-based binary devices delivered moderate PCEs of 10.22% and 8.15%, respectively. After incorporating 30% of 6TIC into the LA1 acceptors, the ternary PSC shows an outstanding PCE of 14.24% with a high VOC of 0.84 V, greatly improved JSC of 22.33 mA cm⁻², and an excellent FF of 75.94% with DPE as additive. Notably, the outstanding performance of the ternary PSC ranks the best ones among the reported ternary solar cells. The improved device performance could be mainly attributed to the integration of complementary properties including absorption and crystallinity, suppressed energy loss during the charge generation process as well as the energy transfer between the acceptors. Our results demonstrated that elaborately selecting acceptors with complementary properties is a promising strategy to construct high-performance ternary PSCs.”

以PBTA-PS为给体，LA1和6TIC为受体，制备了一系列二元和三元PSCs。基于LA1和6TIC的二元器件的PCE分别为10.22%和8.15%。在LA1受体中加入30%的6TIC后，PSCs的PCE为14.24%，Voc为0.84 V，Jsc为22.33 mA cm⁻²，以DPE为添加剂，可获得75.94%的优良FF。器件性能的提高主要归功于吸收和结晶等互补性质的综合，抑制了电荷产生过程中的能量损失以及受体之间的能量转移。实验结果表明，选择具有互补性质的受体是构建高性能PSCs的一个很效的方法。

参考文献：

[1] Adv. Funct. Mater. 2019, 29, 1903596.

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