柔性可拉伸聚合物太阳电池给体材料及器件研究

Flexible polymer solar cells (PSCs) have specific advantages of light-weight, ultra-thin, bendability and can be fabricated based on low-cost solution-processing techniques, exhibiting great potential for commercialization. Despite a certain mechanical stability and ability to anti-bend can be accessed by such flexible PSCs based on traditional plastics, the issue has to be taken into account is the potential external forces during the processing procedures. This requires a certain stretchability or elasticity of PSCs. To attain electron-donating polymeric materials with intrinsic elasticity of stretchability, here we proposed a new strategy to modify the “donor-acceptor” type of conjugated polymers based on benzothiatriazole moiety, which can be achieved by incorporating flexible macromolecular side-chains or main-chain to construct ternary conjugated polymers or “rod-coil” diblock copolymers, respectively. The rod segments define the power conversion efficiency, and the flexible segments determine the stretchability. By blending such copolymers with the electron-accepting materials, the intrinsic stretchable photoactive layer can be afforded. The investigations will focuse on the relationship between copolymer molecular structures with the blending film morphologies, charge carrier mobilities, photovoltaic performances as well as the mechanical properties. Further studies will devote to optimizing processing techniques of the stretchable PSCs to attain high photovoltaic performances associating with remarkable stretchability, which can facilitate the commercialization of such stretchable PSCs.

柔性聚合物太阳电池具有轻薄、可弯曲、可采用低成本印刷工艺制备大面积器件等独特优势，有巨大的产业化前景。尽管基于塑料衬底的柔性聚合物太阳电池具有一定的卷曲特性及机械稳定性，但由于其在加工和使用过程中难免受到弯曲、拉伸等机械外力作用，因此要求器件具有一定的可拉伸性能。本申请拟对基于含有苯并三唑单元的“给体-受体”型共轭聚合物进行修饰，将柔性大分子链引入刚性共轭聚合物的侧链制备三元共轭聚合物，以及引入主链制备刚柔两嵌段聚合物。“刚性”链段决定器件的光电转换效率，“柔性”链段决定器件的可拉伸弹性。拟将发展的聚合物与电子受体共混制作具有本征可拉伸特性的光活性层，研究聚合物的分子结构与相分离形貌、载流子传输、光电转换效率及薄膜机械性能的关系。探索可拉伸器件的制备工艺，制备具有较高光电转换效率的柔性可拉伸聚合物太阳电池器件，为商品化应用奠定理论和实验基础。

聚合物太阳电池具有轻薄、可弯曲、可采用低成本印刷工艺制备大面积器件等独特优势，有巨大的产业化前景，而柔性/可拉伸聚合物太阳电池的概念为有机光伏的工业化生产与市场应用提供了新方案。发展柔性/可拉伸太阳电池的关键在于：（1）开发具有本征可拉伸特性、机械性能良好的活性层材料与基底材料；（2）降低小面积器件在面向大面积“辊对辊”工艺生产过程中产生的能量损失；（3）克服拉伸应力在纳米结构器件的加工过程产生的不良影响。本项目基于具备良好的机械性能与柔性器件发展潜力的全聚合物光伏体系，发展了一系列具有的柔性链段、高吸光系数且能级可调的宽带隙聚合物给体，获得了高光电转换效率的材料体系。后续的研究过程针对原计划的基底设计方案进行了调整。根据柔性/可拉伸器件制备所需要的加工工艺基础，本项目开展了系列研究包括绿色清洁溶剂的开发、膜厚不敏感的材料体系研发与加工工艺控制、以及小面积器件到大面积器件转换过程中的能量损失规避等，取得了一系列比预期更重要的成果。研究不仅为柔性/可拉伸器件的制备打下有利基础，也为推动有机太阳电池的规模化生产与产业发展迈出重要一步。