The efficiencies of dimer-based devices still lag those of their small molecule-based counterparts. This is primarily due to the considerable dihedrals in the dimer skeleton, which compromises the molecular packing, thus influencing the charge generation and nonradiative voltage loss (ΔV_oc,_nr). Herein, we developed two dimeric acceptors with varied π-linkers to investigate the influence of linker-induced conformational lock on ΔV_oc,_nr. We find that the helically lapped O-shaped dimer delivers better intermolecular packing than the planar S-shaped one that incorporates a bulkier π-linker. However, its planar skeleton is instead more favorable for forming a compact and ordered stacking with the host acceptor in ternary blend. This possibly promotes exciton dissociation, thus reducing the nonradiative decay of excited states. Moreover, its longer exciton lifetime could offer additional charge-transfer channels. These contributions effectively minimize ΔV_oc,_nr to 0.195 eV, while delivering a high efficiency approaching 20% in the derived ternary device.

中文翻译：

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二聚体接头诱导的构象锁定与有机太阳能电池中非辐射能量损失的相关性


基于二聚体的器件的效率仍然落后于基于小分子的器件。这主要是由于二聚体骨架中相当大的二面体，这损害了分子堆积，从而影响电荷产生和非辐射电压损失 （ΔV _oc，nr）。在此，我们开发了两个具有不同 π 接头的二聚体受体，以研究接头诱导的构象锁对 ΔV _oc，nr 的影响。我们发现，螺旋重叠的 O 形二聚体比包含更庞大的 π-接头的平面 S 形二聚体提供更好的分子间堆积。然而，它的平面骨架反而更有利于与三元共混的宿主受体形成紧凑而有序的堆叠。这可能会促进激子解离，从而减少激发态的非辐射衰变。此外，其更长的激子寿命可以提供额外的电荷转移通道。这些贡献有效地将 ΔV _oc，nr 降至 0.195 eV，同时在衍生的三元器件中提供接近 20% 的高效率。