虽然目前基于受体-给体-受体（A-D-A）型小分子受体和聚合物给体的光伏器件已取得优异的性能，但是全小分子光伏器件的能量转换效率大部分都比较低。A-D-A型小分子受体的结构、能级和聚集行为等性质与富勒烯衍生物受体之间存在巨大的差异，现有的小分子给体可能不适用于非富勒烯受体。因此，改进小分子给体材料的性能应该是提高全小分子光伏器件能量转换效率的有效策略之一。鉴于此，申请人拟设计合成一系列与A-D-A型窄带隙小分子受体吸收光谱互补的宽带隙小分子给体材料，通过调控其能级，减小由给/受体能级失配造成的能量损失；并且拟通过在小分子给体中引入大共轭稠环单元，提高给体分子的结晶性，促进结晶型互穿网络相分离结构的形成，制备全小分子光伏器件，并揭示给受体材料的分子结构与活性层的微观形貌及器件光伏性能之间的内在联系。本项目将对新材料的开发和全小分子光伏器件性能的提升起到重要的指导作用。

While solar cells based on acceptor-donor-acceptor (A-D-A) non-fullerene acceptors and polymer donors have achieved excellent photovoltaic performance, the power conversion efficiencies (PCEs) of most all-small-molecule solar cells (all-SMSCs) are relatively low. The properties of A-D-A small-molecule acceptors, such as chemical structures, energy levels, aggregation behaviors and so on, are quite different from those of fullerene derivatives. So small-molecule donors that are compatible with fullerene derivatives may be not suitable for non-fullerene acceptors. Therefore, developing new small-molecule donors should be one of the effective strategies to improve the PCEs of all-SMSCs. Based on these, we attempt to design and synthesis new wide bandgap small-molecule donor materials whose absorption spectra are complementary with the A-D-A narrow bandgap acceptors. Through regulating the energy levels of donors, the energy loss could be reduced. Besides, we attempt to introduce conjugated planar fused units to the donors so as to enhance the crystallinity and promote phase separation. Systematic investigations will be carried out on the relationship between chemical structures, blend micro-morphology and photovoltaic performance. The work proposed in this project would provide guidance to the fabrication of highly efficient all-SMSCs.