高效率非富勒烯三元有机光伏器件的研究

In recent years, power conversion efficiency (PCE) of organic photovoltaic devices (OPVs) has been greatly increased by the development of non-fullerene (NF) acceptor materials. However, like majority of organic semiconductor materials, the NF acceptors have full-width at half maximum of only ~ 100 nm. Photon harvesting of active layers is still limited by binary OPVs with NF acceptors. Ternary strategy not only can increase the photon harvesting of active layer but also keep the device in a simple manufacturing process by incorporating the appropriate third component with binary system. This project intends to combine the NF acceptors with the ternary strategy to fabricated NF ternary OPVs with PCE higher than 14% by selecting the active layer materials, regulating the film formation kinetics, optimizing the interfacial modification layer and device structure. Key issues: (1) how to select materials according to physical properties of materials, photovoltaic parameters of two binary devices and so on, which combines with multiple optimization methods to enhance the photon harvesting of the active layer and promote exciton dissociation, charge carrier transport and collection; (2) researching the inherent relationship among of material property, fabrication process, working mechanism and device performance by systematically characterizing the films and devices, aiming at clarifying the main working mechanism and key scientific problems of the device, exploring how to utilize the working mechanism to further improve the device performance.

近年来，非富勒烯受体材料的发展大幅度提升了有机光伏器件的能量转换效率(PCE)。然而，与大多数有机半导体材料一样，非富勒烯受体吸收光谱的半高全宽仅为100nm左右。基于非富勒烯受体的二元器件仍然会限制活性层对光子的俘获。三元策略通过在二元体系中引入适当的第三组份，不仅能够增强活性层的光子俘获，而且使器件保持了简单的制备工艺。本项目拟将非富勒烯受体材料与三元策略相结合，通过甄选活性层材料、调控成膜动力学过程、优化界面修饰层和器件结构，制备出PCE>14%的非富勒烯三元有机光伏器件。研究重点：(1)如何根据材料物性、二元器件光伏参数等甄选材料，结合多重优化手段，增强活性层的光子俘获，同时促进激子解离、载流子传输与收集；(2)通过对薄膜及器件系统地表征，研究材料物性-制备工艺-工作机理-器件性能内在的关系，澄清器件的主要工作机理及关键科学问题，探究如何利用工作机理进一步提高器件性能。

近年来，新型非富勒烯受体材料的研发大幅度提升了有机光伏器件的能量转换效率（PCE）。然而，由于非富勒烯受体材料较窄的吸收半高全宽，基于非富勒烯受体的二元器件仍然会限制有源层对光子的俘获。三元策略是一种有效增强有源层光子俘获的方法且能保持单节器件简单的制备工艺。本项目将非富勒烯受体材料与三元策略相结合，聚焦研究如何构筑高效率非富勒烯三元有机光伏器件，并澄清器件的主要工作机理及相关科学问题。基于材料特性，如带隙、能级、表面能、消光系数等参数甄选有源层材料，结合多种优化手段，协同增强有源层光子俘获及电荷生成和收集。通过对有源层及器件的系统表征，探究材料特性-制备工艺-工作机理-器件性能的内在关系。在该项目的资助下，申请人2019年率先报道效率超过16.2%的双非富勒烯受体的三元有机光伏器件，2020年将该类器件的效率值提高到17.2%。同年，报道了效率超过17.5%的双给体的三元器件。2021年制备出效率超过16%的全小分子三元器件。这些效率值均创造了当时同类器件的效率纪录。此外，申请人提出多种研究器件工作机理的新方法，得到国内外同行的广泛应用和正面评价。相关研究成果共已发表8篇论文，包括5篇ESI高被引论。