Finding effective molecular design strategies and fine tuning the molar ratios of donor/acceptor (D/A) random copolymers to optimize the blend microstructure of the photoactive layer is one of the main long‐standing challenges in developing and fabricating highly efficient all‐polymer solar cells (all‐PSCs). Herein, a random ternary copolymerization strategy to develop four random copolymer acceptors PYEx (x = 10, 20, 30, 40) is used by polymerizing a fused‐ring A–D–A‐type acceptor unit modified from Y5 with a thiophene‐connecting unit and a controlled amount of an ester‐substituted thiophene (EST) unit. Compared with PYT (PYE0) of only Y5‐like units and thiophene units, the ternary copolymers PYEx show slightly down‐shifted lowest unoccupied molecular orbital (LUMO) energy levels, reduced absorption coefficients, and decreased electron mobilities. However, it is also demonstrated that this design approach rationally modifies the molecular aggregations of polymer acceptors, effectively fine tuning the blend morphology and physical mechanisms, and enhances the device performance of the PYEx‐based all‐PSCs. Among them, blends of PYE20 with donor polymer PBDB‐T combine 13.6% power conversion efficiency (PCE). Of particular note is that all of the PYEx‐based devices exhibit the best PCEs of over 13%, indicating the high tolerance on molar ratios.

中文翻译：

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高效三元共聚物通过无规三元共聚物受体实现对摩尔比的高耐受性

寻找有效的分子设计策略并微调供体/受体（D / A）无规共聚物的摩尔比以优化光敏层的共混微观结构是开发和制造高效全聚合物太阳能电池的主要长期挑战之一。单元（所有PSC）。在本文中， 通过将由Y5修饰的稠环A–D–A型受体单元与噻吩-聚合，使用了一种随机三元共聚策略来开发四个无规共聚物受体PYE x（x = 10、20、30、40）。连接单元和受控量的酯取代噻吩（EST）单元。与仅Y5类单元和噻吩单元的PYT（PYE0）相比，三元共聚物PYE x显示出最低未占用分子轨道（LUMO）的能级略有下移，吸收系数降低和电子迁移率降低。但是，也证明了该设计方法合理地修改了聚合物受体的分子聚集，有效地微调了共混物的形态和物理机理，并增强了基于PYE x的全PSC的器件性能。其中，PYE20与施主聚合物PBDB-T的共混物具有13.6％的功率转换效率（PCE）。特别要注意的是，所有基于PYE x的设备都具有超过13％的最佳PCE，这表明对摩尔比的耐受性很高。