扭曲稠环受体分子的取向调制及光电性能研究

The molecular structure and packing mode of the non-fullerene acceptor materials are closely related to the photophysical processes such as light absorption, exciton generation and resolution, charge transport and extraction of the polymer solar cells. The crystallinity of the twisted fused ring receptor is lowered when the molecular structure was distortion, and the mechanism for improving the photoelectric performance of the device is not clear. In this project, the main chain twisted fused-ring small molecule receptor was used as the research object. The grazing incidence wide-angle X-ray scattering technique was used to analyze the orientation and crystal length of the twisted fused ring small molecule and polymer donor blend films. Resonance soft X-ray scattering technique was used to study the phase phase purity and phase size of the active layer blended film. At the same time, the study of carrier dynamics by transient photovoltage/photocurrent technology is of great significance to reveal the relationship between the structural distortion of the fused ring and the photophysical, energy level and photoelectric properties of the device. This study lays a foundation for understanding the structural characteristics of the twisted fused ring small molecule acceptor material. This project provides theoretical and experimental basis for constructing high performance non-fullerene polymer solar cell.

非富勒烯受体材料的分子结构和堆积方式对聚合物太阳电池的光吸收、激子产生和拆分、电荷传输和抽取等光物理过程密切相关，扭曲型稠环受体分子结构扭曲造成结晶性降低，但器件光电性能提升的机制尚不清楚。本项目以主链扭曲型稠环小分子受体为研究对象，采用掠入射广角X射线散射技术对扭曲稠环小分子及其与聚合物给体共混薄膜的取向堆积、结晶长度等微观形貌进行研究。采用共振软X射线散射技术进行活性层共混薄膜的相区纯度、相区尺寸等微观相分离的研究。同时采用瞬态光电压/光电流技术进行载流子动力学方向的研究，对揭示稠环分子结构扭曲与薄膜光物理、能级及器件光电性质之间的作用规律有重要意义，为进一步完善对扭曲型稠环小分子受体材料结构特点的认识奠定基础，本项目研究对构筑高性能非富勒烯聚合物太阳电池器件提供理论和实验依据。

设计并合成新型非富勒烯受体材料是有机太阳电池技术的一个重要研究方向，这对光活性层薄膜形貌、电荷分离效率、载流子迁移率、能量损失和光伏性能产生影响。当一部分有机稠环受体材料的分子结构发生扭曲时，分子间堆积间距增大，材料的结晶性降低，材料光学带隙变宽，吸收光谱发生蓝移，这些现象看似不利于光伏器件性能的提升，然而在前期工作中，我们发现稠环受体分子结构的适度扭曲有利于提升有机光伏器件的性能。针对扭曲稠环受体材料存在着分子结构与性能之间的构效关系不明确这一关键科学问题，本项目开展了扭曲型稠环有机光伏受体材料的分子结构设计合成、材料理化性质测定、活性层形貌调控、微纳结构精细表征、光伏器件研制及器件物理机制等研究工作，系统探索了扭曲稠环有机光伏受体材料结构、取代基团单元、活性层成膜方式对分子堆积和光电性能的影响规律，进一步理解扭曲型稠环小分子受体材料的结构特点，设计并发展了20余种新型扭曲稠环有机光伏受体材料，研制出系列基于扭曲稠环受体的高性能有机太阳电池器件。项目执行期间共发表SCI论文15篇。