A series of soluble C70-derivatives (C70-PCBX) was synthesized by varying the alkyl chain length of the adduct (X = R1, R3, R5, R7, R9) attached to the C70-polyhedron. After blending with P3HT, bulk heterojunction polymer solar cells were fabricated, and their performances were evaluated. As the alkyl chain length increased, phase segregation between the P3HT and C70-PCBX domains in the P3HTâ:âC70-PCBX blend active layer increased, which enhanced the device performance to a moderate degree. The performance enhancement may have been due to the increased solubility and self-aggregation of C70-PCBX as a result of the longer alkyl chains, as was predicted by molecular simulations. The nanomorphologies of the P3HTâ:âC70-PCBX active layers offered an explanation for the trend in solar cell performance: as the series progressed from C70-PCBR1 to C70-PCBR7, the open circuit voltage and the short circuit current gradually increased, followed by a slight drop for C70-PCBR9. An optimal overall power conversion efficiency was observed for C70-PCBR7 with a P3HTâ:âC70-PCBR7 blend ratio of 1â:â0.8 to 1â:â0.9.
通过改变连接到 C70 多面体上的加合物(X = R1、R3、R5、R7、R9)的烷基链长度,合成了一系列可溶性 C70 衍
生物(C70-PCBX)。在与 P3HT 混合后,制造出了体异质结聚合物太阳能电池,并对其性能进行了评估。随着烷基链长度的增加,P3HTâ:âC70-PCBX共混活性层中P3HT和C70-PCBX畴之间的相分离增加,这在一定程度上提高了器件的性能。正如分子模拟所预测的那样,性能提高的原因可能是烷基链变长导致C70-PCBX的溶解度和自聚集能力提高。P3HTâ:âC70-PCBX活性层的纳米形态为太阳能电池的性能趋势提供了解释:从C70-PCBR1到C70-PCBR7,开路电压和短路电流逐渐增加,C70-PCBR9则略有下降。当P3HTâ:âC70-PCBR7的混合比例为1â:â0.8至1â:â0.9时,C70-PCBR7的整体功率转换效率达到最佳。