高效率三元有机光伏器件的制备及其机理研究

Developing highly efficient, low cost and green photovoltaic materials and devices is a major strategic demand for sustainable development. Organic photovoltaic materials and devices have been the focus of research due to the low cost, friendly environment, flexibility and so on. The power conversion efficiency (PCE) of donor/acceptor bulk heterojunction organic photovoltaic devices has exceeded 10% and the highest record has reached 11.7%. Due to the narrow absorption properties of organic materials, ternary organic photovoltaic devices are expected to be an effective strategy to further improve the performance of the device. In this project, we focus on the substrate modification to reduce the incident light loss and the selection of absorption complementary ternary photovoltaic materials as the active layer to enhance the photon harvesting. With the synergistic optimization of the preparation process and device structure, the ultimate goal is to obtain PCE over 12% of ternary organic photovoltaic device. The research key points focus on the selection of materials based on their energy level, absorption coefficient and compatibility, as well as adjusting the film forming dynamic process according to the properties of used materials. It is not only to enhance the photon harvesting capability and widen photon harvesting range of the active layer, but also to form the interpenetrated network structure for the better exciton dissociation, charge carrier transport and collection. The key scientific issues among materials properties, preparation process and device performance should be clarified by investigating the electric, optical and morphology characterization of active layers. The working mechanism of ternary solar cells is to be fully understood by clarifying the loss mechanism and performance decay process of ternary organic photovoltaic cells.

研发高效率、低成本、绿色光伏材料与器件是实现可持续发展的重大战略需求。有机光伏材料与器件由于其成本低、环境友好、柔性等优点，一直是研究焦点。二元有机光伏器件的能量转换效率(PCE)已突破10%，最高记录已达到11.7%。由于有机材料光吸收范围窄，三元有机光伏器件有望成为进一步提高器件性能的有效策略。本项目拟采用衬底修饰降低入射光损耗、吸收光谱互补的三种材料制备有源层增强光子俘获，协同制备工艺与器件结构的优化，制备出PCE超过12%三元有机光伏器件。研究重点：如何从能级结构、消光系数、兼容性等方面甄选材料，结合材料物性调控有源层成膜动力学过程，既增强有源层光子俘获能力又拓展俘获范围，同时形成有利于激子解离、载流子传输与收集的互穿网络结构；表征有源层光学、电学、形貌学等参数，澄清材料物性-制备工艺-器件性能之间的关键科学问题；研究三元有机光伏器件的损耗机制及性能衰减动力学过程，澄清其工作机理。

近年来，有机光伏器件的光电转换效率得到了快速发展，主要是新型给受体材料及有源层的设计、优化，器件及界面工程的发展。.申请人较早聚焦于三元有机光伏器件的研究，率先报道了有效调控有源层成膜动力学过程的新方法、研究机理的新手段，并得到同行广泛认可及采用。提出了倒置熏蒸、倒置退火的新工艺；提出研究纯给（受）体器件的Jsc，研究双给（受）体间激子动力学过程的新方法。.聚焦在甄选材料、优化工艺、澄清机理上，报道了系列高效率三元有机光伏器件的研究成果。重要成果陆续发表在Sci. Bull. 64 (2019) 504 (SCI引用116次), Sci. Bull. 65 (2020) 538，中国科学杂志社以“新纪录：16.27%！ 三元聚合物太阳能电池”和“三元有机太阳能电池：效率17.22%”为题进行重点报道。经中国计量科学院验证效率为16.8%，第三方验证报告请见附件。2020年在Advanced Energy Materials上报道了效率为17.4%的三元有机光伏器件。.利用第三组分与主体系材料吸收光谱的互补性，增强三元有源层的光子俘获范围与能力，制备出一系列高效率的三元有机光伏器件。利用吸收光谱互补的双给体材料，制备高效率三元有机光伏器件，相关研究成果发表在Adv. Energy Mater. 8 (2018) 1702854; Nano Energy 60 (2019) 768。利用吸收光谱互补的双受体材料，制备出高效率三元有机光伏器件，该工作发表在Nano Energy 45 (2018) 177。申请人率先提出以二元器件光伏参数的互补性作为甄选材料的新策略，为制备高性能三元有机光伏器件提供了一个新思路。以光学带隙接近的IT-M与ITIC (吸收光谱基本重合)为受体，J71为给体材料制备出光伏参数具有互补性且PCE为10.68%和10.65%的二元器件。集成两个二元器件光伏参数的优势，制备出PCE为11.60%三元有机光伏器件，该工作发表在ACS Energy Lett. 7 (2018) 555。.申请人将高结晶性、高载流子迁移率的MF1作为第三组分引入PBDB-T-2Cl:BP-4F主体系中，制备出300 nm厚膜三元有机光伏器件的FF和PCE达到71.62%和14.57%，该工作发表在Energy Environ. Sci. 13 (2020) 958。