侧链非共价键作用诱导聚合物链聚集的窄带隙聚合物及其高效率电池器件研究

Narrow bandgap polymers by alternating donating (D) unit with accepting (A) unit are the focus of materials research in achieving high-efficiency organic solar cells. The highest power conversion efficiency of single-layer polymer solar cells (PSCs) has been increased above 10%. PSC power conversion efficiencies, However, are still constrained by the relative low fill factors (typically lower than 70%) of narrow bandgap polymers. In this proposal, four series of novel narrow bandgap polymers, with their solid-phase aggregation induced by side-chains on both D and A units. Intra- or intermolecular intereactions can be constructed among the functional side-chains introduced on D and A units of narrow bangap polymers. The synthetic routes for the polymers will be expored and optimized. The correlation between polymer structures and their absorption, electrochemical, crystallization and hole mobility will be conducted. Both temperature and concentration dependent absorption of polymers will be investigated. By preparation and optimization of PSCs with polymer and fullerene derivative as active layers, we will study the dependance of device performance upon device structure and fabrication processing. The correlation bwtween device processing with morphology of actve layers, hole mobility and device perofomance with be elaborated. The phase separation of active layers in both horizontal and vertical directions will be studied to reveal the the aggregation behaviours of polymers induced by the functional side-chains. This project is importanct is enriching design concept for narrow bandgap polymers and promoting high-efficiency polymer solar cells.

供-受体单元交替结构的窄带隙聚合物是目前获取高效率有机太阳能电池的材料研究重点，其最高电池光电转化效率已突破10%。但是，如何提高其填充因子(<70%)，进一步提高窄带隙聚合物电池效率是当前科学研究的难点。本项目拟探索四类新型的通过在供-受体单元引入可构建相互作用的功能侧链诱导聚合物主链固态聚集的窄带隙聚合物；探索及优化聚合物的合成路线，表征聚合物结构对其光学、电化学、结晶、空穴传输等性能，考察聚合物光谱随温度和浓度的变化规律；制备、优化聚合物与富勒烯衍生物为活性层的太阳能电池，考察器件结构、制备工艺对光伏性能的影响，关联器件制备工艺与共混膜相态、载流子传输和光伏性能，探讨活性层在二维尺度上的相分离、验证侧链诱导聚合物链固相聚集拓展聚合物膜吸收、提高器件填充因子的设计理念。该项目对于丰富聚合物结构设计，推进高效率太阳能电池的研究具有重要意义。

本项目针对高效率聚合物有机太阳能电池中填充因子较低 (通常<70%)、活性层相分离的形貌控制难题，从聚合物给体和稠环电子受体材料设计以及器件方面入手，通过开发新型利用侧链非共价键诱导共轭主链固相聚集的聚合物给体材料、分子构象锁定的新型稠环电子受体，结合器件优化、器件物理和器件工程，实现了光电转换效率超过14%的单节聚合物太阳能电池。主要研究工作包括：1) 完成了稠环供体单元包括苯并二噻吩和苯并二呋喃、及非稠环供体单元包括噻吩-苯-噻吩和噻吩并噻吩-苯-噻吩并噻吩侧链功能化的化学修饰方法、及其窄带隙聚合物的合成探索与优化；2) 研究了利用共轭单元间的非共价键作用诱导聚合物主链固态聚集行为，优化活性层的相分离，提高电池器件性能；3) 针对受体-给体-受体(A-D-A)型稠环电子受体分子，通过设计新型吡咯并二噻吩稠环给体单元、稠环给体单元分子工程、受体分子受体端基工程，获取了系列分子构象锁定、分子堆积方式均一化的稠环电子受体材料，与聚合物给体共混制备了免器件后处理的高效率as-cast器件；4) 利用稠环电子受体材料，结合并联叠层和三元光伏器件策略，获取了系列世界先进水平的电池器件。