聚噻吩并[3,4-b]噻吩类电子受体材料设计、合成及在全聚合物太阳能电池中的研究

All-polymer solar cells are attractive as alternatives to fabricate morphology and mechanically stable solar cells, especially with well applied prospects in portable charging, integrated photovoltaic building and wearable electronic devices. However, the photovoltaic performance of all-polymer solar cells still lag behind that of state-of-the-art small molecule-based solar cells mainly due to the difficulty to form well phase-separated D/A interpenetrating networks on a nanoscale. The project is aimed to develop novel polymer acceptors and fabricate high performance all-polymer based devices by fine tuning the blend films morphology though molecular engineering. Based on the design strategy of “enhancing the quinoidal resonance of D-A system”, a series of poly thieno[3,4-b]thiophene-based electron acceptors will be synthesised with superior photoelectrical properties, such as high light absorption, low energy bandgap, good planarity and rigidity and high electron mobility. More importantly, the morphology of the blend films can be fine tuned by elaborately designing molecular structure with different backbone and side chain. Thus, all-polymer devices with high efficiency will be realized by combining molecular engineering with device enegineering. The reaserch will provide a platform for developing highly efficient all-polymer solar cells though extention of new n-type polymers and exploration of the overall relationship between polymer acceptor’s structure and device performances, which will boost the application of all-polymer solar cells in the next-generation flexible electronic devices.

全聚合物太阳能电池因其良好的形貌稳定性和机械稳定性而被认为在便携式充电、光伏一体化建筑及可穿戴电子器件等方面具有良好的应用前景。然而，全聚合物太阳能电池的光电转换效率显著低于由小分子受体材料制备的太阳能电池器件，主要是由于共混薄膜在纳米尺度上难以形成良好的相分离。本项目旨在发展新型高性能聚合物受体材料，通过分子工程调控共混薄膜形貌，组装高性能全聚合太阳能电池。采用“增强D-A体系醌式共振”策略，设计并合成具有强吸收、窄带隙、分子平面性好及高电子迁移率的聚噻吩并[3,4-b]噻吩类非富勒烯受体材料，通过选用不同的给体/桥连结构单元，调控材料的光电物理性质及共混薄膜的相分离，结合器件优化实现高性能全聚合物太阳能电池制备。该研究项目有利于拓展n-型聚合物材料的发展，通过对材料与器件性能的总体构效关系探索，建立制备高性能全聚合物太阳能电池的研究模型，进一步推动全聚合物太阳能电池的发展。

本项目旨在发展新型受体材料，结合器件工程制备高性能有机聚合物太阳能电池器件，深入了解电子受体材料分子结构-器件性能的总体构效关系。取得的结果为：①提出了利用高度兼容的受体协同“二合一”受体合金策略，精细调控两个受体材料的比例，实现对合金受体能级的精准调节，提高器件电荷传输效率，降低材料体系非辐射能量损失，实现高光电转换效率； ②二维π-拓展小分子受体材料设计策略，调控分子间相互作用，改善共混薄膜形貌及相分离，促进激子解离并抑制电荷复合；③提出N杂受体策略，增强LE-CT杂化，降低共混体系非辐射能量损失，开发兼具高透过率和高效率的半透明有机聚合物太阳能电池；④提出发展高平面性、高迁移率的聚合物受体材料，发展了具有高电子迁移率（0.54 cm2 V-1 s-1）的聚合物受体材料PSV。这些材料的开发及器件的构筑，对深入理解分子结构-器件性能关系提供了研究对象，有利于进一步推动高效率、高稳定性有机太阳能电池的发展。