Herein, we have designed a ternary system comprising of two small molecules (B2 and B3), as donor and a narrow bandgap non-fullerene small molecule acceptor Y6. The chemical structures of B2 and B3 are close to each other but their absorption spectra are complementary with different energy levels. Using these small-molecules, a ternary organic solar cell was fabricated. The presence of B2 in the B3:Y6 blend increases the photon harvesting as well as also forms cascade energy level arrangement which benefits assisting the balancing between the dissociation of excitons into free charge carriers and their subsequent charge transfer between the two donors (B2 and B3) and the acceptor (Y6). Moreover, the photoluminescence spectroscopy analysis has revealed efficient energy transfer from B2 to B3, which resulted in the effective excitons utilization in ternary device. This way, we have been able to achieve over efficiency of about 12.88% with energy loss of 0.54 eV for the ternary device, greater than that for binary devices i.e., 8.73% with energy loss of 0.51 eV and 9.26% with energy loss of 0.61 eV for B2:Y6 and B3:Y6, respectively. This low energy loss is one of the lowest in the fullerene free ternary photovoltaic devices based on all small molecules (donor and acceptors).

在此，我们设计了一个三元系统，包含两个小分子（B2和B3）作为供体和一个窄带隙非富勒烯小分子受体Y6。B2和B3的化学结构彼此接近，但它们的吸收光谱具有不同能级的互补性。使用这些小分子，制造了三元有机太阳能电池。的存在B2的B3：Y6混合增加了光子捕获以及还形成了利益协助激子的离解之间的平衡成为自由载流子级联能级的安排和两个捐助者之间的后续电荷转移（B2和B3 ) 和受体 ( Y6)。此外，光致发光光谱分析揭示了从B2到B3 的有效能量转移，这导致了三元器件中激子的有效利用。通过这种方式，我们已经能够实现约 12.88% 的超效率，三元器件的能量损失为 0.54 eV，高于二元器件的效率，即能量损失为 0.51 eV 的 8.73% 和能量损失为 0.61 的 9.26%分别为B2:Y6和B3:Y6 的eV 。这种低能量损失是基于所有小分子（供体和受体）的无富勒烯三元光伏器件中最低的之一。