Xiao Xinyu, Yi Nan, Yao Ge, Lu Jianing, Leng Shifeng, Liu Feng, Hu Ming, Yuan Zhongyi, Zhou Weihua
School of Material Science and Engineering, Nanchang University, 999 Xuefu Avenue, Nanchang 330031, China.
School of Chemistry and Chemical Engineering, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, China.
ACS Appl Mater Interfaces. 2020 Dec 30;12(52):58082-58093. doi: 10.1021/acsami.0c17049. Epub 2020 Dec 17.
The mechanism of how the solvent type influences photovoltaic performance and thermal stability of non-fullerene organic solar cells remains unexplored. In this article, the well-known PTB7-Th was selected as a donor, while F8IC was used as an acceptor. The PTB7-Th:F8IC processed from chloroform (CF) exhibited a superiorly higher power conversion efficiency (PCE) of 10.5%, in contrast to the specimen processed from chlorobenzene (CB) of 6.8%. In addition, upon thermal annealing at 160 °C for 120 min, the device processed from CF was more stable than that processed from CB. The incorporation of perylene diimide derivative TBDPDI-C, serving as the third additive, could also obviously improve the PCE value and thermal stability of PTB7-Th:F8IC processed from CB. According to ultraviolet spectroscopy, atomic force microscopy, transmission electron microscopy, and grazing incidence wide-angle X-ray scattering analyses, the enhanced photovoltaic performance and thermal stability are mainly attributed to formation of PTB7-Th nanofibers and appropriate aggregation of F8IC. The interaction free energy calculated using water and diiodomethane contact angles reveals that PTB7-Th well disperses in CB and tends to aggregate in CF, while F8IC aggregates strongly in CB. The preaggregation matching of the donor and acceptor in solution is essential for the optimization of morphology, efficiency, and thermal stability. The findings in this article could provide useful guidelines to fabricate efficient and thermally stable organic solar cells simply by analyzing the surface energy of components processed from different solvents.
溶剂类型如何影响非富勒烯有机太阳能电池的光伏性能和热稳定性的机制仍未被探索。在本文中，选用了著名的PTB7-Th作为供体，而F8IC用作受体。由氯仿（CF）加工而成的PTB7-Th:F8IC表现出高达10.5%的卓越功率转换效率（PCE），相比之下，由氯苯（CB）加工的样品的功率转换效率为6.8%。此外，在160°C下热退火120分钟后，由CF加工的器件比由CB加工的器件更稳定。作为第三种添加剂的苝二酰亚胺衍生物TBDPDI-C的加入，也能显著提高由CB加工的PTB7-Th:F8IC的PCE值和热稳定性。根据紫外光谱、原子力显微镜、透射电子显微镜和掠入射广角X射线散射分析，光伏性能和热稳定性的提高主要归因于PTB7-Th纳米纤维的形成和F8IC的适当聚集。利用水和二碘甲烷接触角计算得到的相互作用自由能表明，PTB7-Th在CB中分散良好，在CF中倾向于聚集，而F8IC在CB中强烈聚集。供体和受体在溶液中的预聚集匹配对于形貌、效率和热稳定性的优化至关重要。本文的研究结果可为通过简单分析由不同溶剂加工的组分的表面能来制备高效且热稳定的有机太阳能电池提供有用的指导。
