Huang Tzu-Yen, Yan Hongping, Abdelsamie Maged, Savikhin Victoria, Schneider Sebastian A, Ran Niva A, Nguyen Thuc-Quyen, Bazan Guillermo C, Toney Michael F
Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory Menlo Park CA USA
Department of Chemical Engineering, Stanford University Stanford CA USA.
RSC Adv. 2019 Jan 30;9(8):4106-4112. doi: 10.1039/c8ra10488c.
The performance of organic solar cells (OSCs) depends crucially on the morphology in bulk heterojunctions (BHJs), including the degree of crystallinity of the polymer and the amount of each material phase: aggregated donor, aggregated acceptor, and molecular mixed donor : acceptor phase. In this paper, we report the BHJ morphology of as-cast blend films incorporating the polymer PIPCP as the donor and [6,6]-phenyl-C-butyric acid methyl ester (PCBM) as the acceptor. Tracking the scattering intensity of PCBM as a function of PCBM concentration shows that PCBM aggregates into donor-rich domains and there is little to no phase where the PCBM and PIPCP are intimately mixed. We further find that on blending the scattering peak due to PIPCP ordering along the backbone increases with decreasing PIPCP fraction, which is attributed to improved ordering of PIPCP due to the presence of PCBM. Our results suggest that the improved ordering of PIPCP along the backbone (consistent with an increased conjugation length) with blending contributes to the observed low open-circuit voltage energy loss.
有机太阳能电池（OSC）的性能关键取决于本体异质结（BHJ）中的形态，包括聚合物的结晶度以及各材料相的含量：聚集的给体、聚集的受体和分子混合的给体 : 受体相。在本文中，我们报道了以聚合物PIPCP作为给体、[6,6]-苯基-C-丁酸甲酯（PCBM）作为受体的浇铸共混膜的BHJ形态。跟踪PCBM的散射强度随PCBM浓度的变化表明，PCBM聚集形成富含给体的区域，几乎不存在PCBM和PIPCP紧密混合的相。我们进一步发现，在共混时，由于PIPCP沿主链有序排列而产生的散射峰随PIPCP含量的降低而增加，这归因于PCBM的存在使PIPCP的有序性提高。我们的结果表明，共混时PIPCP沿主链的有序性提高（与共轭长度增加一致）有助于观察到的低开路电压能量损失。
