Chang Kai, Li Yaxing, Du Gengxin, Zhong Mingyao, Yang Ping, Zhu Yulin, He Feng, Mi Baoxiu, Zhao Xinyan, Deng Weiwei
Institute of Advanced Materials (IAM), Key Laboratory for Organic Electronics & Information Displays (KLOEID), Nanjing University of Posts & Telecommunications (NUPT), Nanjing 210023, China.
Department of Mechanics and Aerospace Engineering, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China.
ACS Appl Mater Interfaces. 2020 Jun 17;12(24):27405-27415. doi: 10.1021/acsami.0c03632. Epub 2020 Jun 8.
Developing scalable processing methods with low material waste is still one of the remaining challenges for organic photovoltaics (OPVs) to become a practical renewable energy source. Here, we report the first study on printing active layers of OPVs containing non-fullerene acceptors (NFAs) by electrospray (ES). The properties of the solvent significantly influence the interfacial morphology of ES-printed organic thin-films, and solvent engineering is essential to facilitate the formation of efficient active-layer films. We introduce low-vapor-pressure non-halogen solvent -xylene (OXY) into the high vapor pressure solvent of chloroform to form a binary solvent system with appropriate evaporation time, electric conductivity, and solubility. The characteristic times of the ES process using binary solvents are quantified to provide insights into the dynamic formation of thin films. A longer droplet evaporation time with decent solubility collectively decrease the roughness and domain size of the polymer/NFA blend films, thus increase the photocurrent and fill factor of the ES-printed OPV devices. The ES-printed active layers show enhanced crystallinity and phase separation of NFA molecules than the spin-coated films. The champion cell with an ES-printed PTB7-Th:FOIC active layer exhibits a power conversion efficiency of 9.45%, which is on par with the spin-coated cells and is among the highest of spray-deposited organic solar cells to date. This work demonstrates that ES is an effective method to prepare OPVs on NFAs.
开发具有低材料浪费的可扩展加工方法仍然是有机光伏（OPV）成为实用可再生能源所面临的剩余挑战之一。在此，我们报告了第一项关于通过电喷雾（ES）印刷含有非富勒烯受体（NFA）的OPV活性层的研究。溶剂的性质显著影响ES印刷有机薄膜的界面形态，溶剂工程对于促进高效活性层薄膜的形成至关重要。我们将低蒸气压非卤代溶剂——二甲苯（OXY）引入高蒸气压溶剂氯仿中，以形成具有适当蒸发时间、电导率和溶解度的二元溶剂体系。对使用二元溶剂的ES过程的特征时间进行了量化，以深入了解薄膜的动态形成过程。具有适度溶解度的较长液滴蒸发时间共同降低了聚合物/NFA共混薄膜的粗糙度和畴尺寸，从而提高了ES印刷OPV器件的光电流和填充因子。与旋涂薄膜相比，ES印刷的活性层显示出增强的结晶度和NFA分子的相分离。具有ES印刷PTB7-Th:FOIC活性层的冠军电池表现出9.45%的功率转换效率，与旋涂电池相当，是迄今为止喷雾沉积有机太阳能电池中效率最高的之一。这项工作表明ES是在NFA上制备OPV的有效方法。
