Rational Design of Conjugated Polymers with Cleavable Side Chains to Achieve Morphological Stability of Polymer Solar Cells

非技术性总结：在材料研究部聚合物项目的支持下，查佩尔山的北卡罗来纳州教授魏友打算探索具有可裂解侧链的共轭聚合物的合理设计，旨在增强此类共轭聚合物基太阳能电池的稳定性。该项目的成功将大大提高对侧链在平衡共轭聚合物的溶解性和此类聚合物基太阳能电池的热稳定性方面的功能的理解，并导致具有改进的热稳定性和高效率的聚合物太阳能电池。该项目的所有参与者将有机会从合成到设备制造进行跨学科学习，以及通过一些已建立的合作使用复杂的表征工具。 PI的团队将积极招募和培养不同背景的学生，并为公众和K-12学生开展外联活动。技术概要：通常，用于高效太阳能电池的共轭聚合物通常显示出较低的玻璃化转变温度，导致此类太阳能电池在热操作期间不稳定。热去除可裂解侧链是在溶液加工过程中提供共轭聚合物所需的溶解性，并在成膜后通过热去除侧链重新获得共轭聚合物的高玻璃化转变温度的有效方法。You小组最近提出了一种平衡的方法，其中一些侧链将被切割以获得形态稳定性，同时保留其他侧链以保持预先建立的形态，从而在很大程度上保持效率。该项目的目标是：（1）设计合成聚具有可裂解侧链和未取代的噻吩单元的（噻吩），以进一步提高效率和稳定性，（2）开发用于裂解烷基链的更温和的方法，以使对形态的热影响最小化，（3）进行形态研究，以在这些模型系统内开发结构-形态-稳定性-效率关系，以及（4）探索高性能共轭聚合物和小分子受体中的可裂解侧链，以实现高器件效率和高形态稳定性。该项目的成功将导致低温工艺的开发，以实现侧链的裂解，实现高形态稳定性和高效率的PSC，并阐明结构-形态-稳定性-效率的关系。该奖项反映了NSF的法定使命，并已被认为是值得支持的评估使用基金会的智力价值和更广泛的影响审查标准。

NON-TECHNICAL SUMMARY:With the support of the Polymers Program in the Division of Materials Research, Professor Wei You of the University of North Carolina at Chapel Hill intends to explore rational design of conjugated polymers with cleavable side chains, aiming to enhance the stability of such conjugated polymer-based solar cells. The success of this project would significantly enhance the understanding of the function of side chains in balancing the solubility of conjugated polymers and the thermal stability of such polymer-based solar cells, and result in polymer solar cells of improved thermal stability and high efficiency. All participants in this project will have the opportunity for interdisciplinary learning from synthesis to device fabrication, as well as sophisticated characterization tools via a number of established collaborations. The PI's group will actively recruit and train students of diverse backgrounds, in addition to conducting outreach activities for the general public and K-12 students.TECHNICAL SUMMARY:Typically, conjugated polymers used in high efficiency solar cells often show low glass transition temperatures, leading to instability of such solar cells during operation by heat. Thermally removing cleavable side chains is an effective approach to offer the necessary solubility of conjugated polymers during solution processing, and re-gain the high glass transition temperature of conjugated polymers via thermal removal of side chains after the film formation. The You group recently proposed a balanced approach where some side chains would be cleaved to gain morphological stability while keeping other side chains to maintain the pre-established morphology to largely retain the efficiency. The objectives of this project are: (1) to design the synthesis of poly(thiophene)s with cleavable side chains and unsubstituted thiophene units to further improve the efficiency and stability, (2) to develop milder methods for cleaving alkyl chains to minimize the thermal impact on morphology, (3) to conduct morphological investigations to develop structure-morphology-stability-efficiency relationships within these model systems, and (4) to explore the cleavable side chains in high-performance conjugated polymers and small molecule acceptors to achieve high device efficiency and high morphological stability. The success of this project would lead to development of a low-temperature process to achieve the cleavage of side chains, achieving PSCs of high morphological stability and high efficiency, and elucidating the structure-morphology-stability-efficiency relationships.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.