Kim Saeah, Choi Huijeong, Lee Myeongjae, Jung Hyeseung, Shin Yukyung, Lee Seul, Kim Kyungkon, Kim Myung Hwa, Kwak Kyungwon, Kim BongSoo
Department of Chemistry & Nano Science, Ewha University, Seoul 03760, Republic of Korea.
Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea.
Polymers (Basel). 2023 Mar 8;15(6):1354. doi: 10.3390/polym15061354.
Organic solar cells (OSCs) demonstrating high power conversion efficiencies have been mostly fabricated using halogenated solvents, which are highly toxic and harmful to humans and the environment. Recently, non-halogenated solvents have emerged as a potential alternative. However, there has been limited success in attaining an optimal morphology when non-halogenated solvents (typically -xylene (XY)) were used. To address this issue, we studied the dependence of the photovoltaic properties of all-polymer solar cells (APSCs) on various high-boiling-point non-halogenated additives. We synthesized PTB7-Th and PNDI2HD-T polymers that are soluble in XY and fabricated PTB7-Th:PNDI2HD-T-based APSCs using XY with five additives: 1,2,4-trimethylbenzene (TMB), indane (IN), tetralin (TN), diphenyl ether (DPE), and dibenzyl ether (DBE). The photovoltaic performance was determined in the following order: XY + IN < XY + TMB < XY + DBE ≤ XY only < XY + DPE < XY + TN. Interestingly, all APSCs processed with an XY solvent system had better photovoltaic properties than APSCs processed with chloroform solution containing 1,8-diiodooctane (CF + DIO). The key reasons for these differences were unraveled using transient photovoltage and two-dimensional grazing incidence X-ray diffraction experiments. The charge lifetimes of APSCs based on XY + TN and XY + DPE were the longest, and their long lifetime was strongly associated with the polymer blend film morphology; the polymer domain sizes were in the nanoscale range, and the blend film surfaces were smoother, as the PTB7-Th polymer domains assumed an untangled, evenly distributed, and internetworked morphology. Our results demonstrate that the use of an additive with an optimal boiling point facilitates the development of polymer blends with a favorable morphology and can contribute to the widespread use of eco-friendly APSCs.
具有高功率转换效率的有机太阳能电池（OSCs）大多是使用卤化溶剂制造的，这些溶剂对人类和环境具有高毒性和危害性。最近，非卤化溶剂已成为一种潜在的替代方案。然而，当使用非卤化溶剂（通常为 - 二甲苯（XY））时，在获得最佳形态方面取得的成功有限。为了解决这个问题，我们研究了全聚合物太阳能电池（APSCs）的光伏性能对各种高沸点非卤化添加剂的依赖性。我们合成了可溶于XY的PTB7 - Th和PNDI2HD - T聚合物，并使用XY与五种添加剂：1,2,4 - 三甲基苯（TMB）、茚满（IN）、四氢化萘（TN）、二苯醚（DPE）和二苄醚（DBE）制备了基于PTB7 - Th:PNDI2HD - T的APSCs。光伏性能按以下顺序确定：XY + IN < XY + TMB < XY + DBE ≤ 仅XY < XY + DPE < XY + TN。有趣的是，所有用XY溶剂体系处理的APSCs的光伏性能都优于用含1,8 - 二碘辛烷的氯仿溶液（CF + DIO）处理的APSCs。通过瞬态光电压和二维掠入射X射线衍射实验揭示了这些差异的关键原因。基于XY + TN和XY + DPE的APSCs的电荷寿命最长，它们的长寿命与聚合物共混膜形态密切相关；聚合物域尺寸在纳米尺度范围内，并且共混膜表面更光滑，因为PTB7 - Th聚合物域呈现出无缠结、均匀分布和相互连接的形态。我们的结果表明，使用具有最佳沸点的添加剂有助于开发具有良好形态的聚合物共混物，并有助于环保型APSCs的广泛应用。
