活性层混合溶剂的选择对高分子太阳能电池性能的影响

高分子有机太阳能电池因为其简单的制作工艺和轻便稳定的特性而引起人们的广泛研究。控制活性层的形貌对于提高有机太阳能电池的光电性能有着至关重要的意义。使用两种不同的混合溶剂(氯仿/1,8-二碘代辛烷和氯苯/1,8-二碘代辛烷)来制备PTB7-Th:PC_(70)BM活性层。发现使用氯苯/1,8-二碘代辛烷能使活性层获得更好的相分离效果,从而有利于光的吸收和电荷的分离。相对于氯仿/1,8-二碘代辛烷,使用氯苯/1,8-二碘代辛烷的太阳能电池的光电转化效率从7.21%大幅提高到了8.86%。这主要来自短路电流密度(从15.1 mA/cm~(-2)提高至16.7 mA/cm~2)和填充因子(从61.2%提高至66.3%)的提高。结果表明使用氯苯/1,8-二碘代辛烷作为混合溶剂有利于制备高性能的基于PTB7-Th:PC_(70)BM的有机太阳能电池。

Mix-Solvent Effect of the Active Layer on the Performance of Organic Solar Cells

Polymer based organic solar cells have attracted a lot of attentions due to their properties of light weight, high stability, and simple fabrication process. Control the morphology of active layers plays very important roles for improving the performance of organic solar cells. In this work, we respectively used mix-solvents of chloroform/1,8-diiodooctone and chlorobenzene/1,8-diiodooctone for processing PTB7-Th:PC70BM based active layers. We find that using chlorobenzene/1,8-diiodooctone resulted in an improved morphology with good phase separation, which is beneficial for light absorption and charge dissociation. Compared with using chloroform/1,8-diiodooctone, the solar cell based on chlorobenzene/1,8-diiodooctone exhibited an improved power conversion efficiency from 7.21 to 8.86 %. The improvement mainly came from the largely enhanced short circuit current density (15.1-16.7 mA/cm2) and fill factor (61.2-66.3 %). Our results indicate that using mix-solvent of chlorobenzene/1,8-diiodooctone for processing PTB7-Th:PC70BM based active layer is advantageous for fabricating high performance organic solar cells.