基于萘并多氮杂环核心的线型A1-D-A2-D-A1类小分子受体光伏材料研究

基于Y6的有机聚合物太阳能电池效率已超过18%，展现良好的应用前景。但该类材料存在结晶性弱、HOMO能级高、稳定性差、器件Voc低等不足。其弧形分子结构不利于分子堆积和载流子传输。本项目拟深入研究以萘并多氮杂环为核心的A1-D-A2-D-A1型小分子受体及其构效关系。同Y6相比，这类材料具有相对线型的分子结构。刚性萘并多氮杂环的设计将提升材料结晶性，降低其HOMO能级，改善稳定性。其HOMO能级的降低，使得以前众多优异的深HOMO能级的给体材料能够与之匹配，利于更高效光伏器件的实现。通过萘并多氮杂环核心、稠合核心骨架杂环和末端吸电子基团的优化设计，综合调控这类小分子受体的光谱吸收、能级水平、电荷传输、共混性和结晶性，解决Y6分子体系中存在的关键科学问题。最终通过双组份和多元共混器件的系统研究，构筑基于多元共混器件为子电池的叠层器件，突破有机聚合物太阳能电池的效率瓶颈，为商业化应用奠定基础。

The efficiency of organic/polymer solar cells based on Y6 acceptor has exceeded 18%, which exhibits good practical application prospect. However, the Y6 molecular system still exists some shortcomings, such as weak crystallinity, high HOMO level, poor stability and low Voc in devices. Also, its arched structure is unbeneficial to the molecular stacking and carrier transfer. In this project, deep studies will be performed on A1-D-A2-D-A1 type small molecular acceptors based on naphthopolyazacycle core and their structure-property relationship. Compared with Y6, this type of small molecular acceptors has the relatively linear structure. At the same time, the introduction of naphthopolyazacycle skeleton will improve the crystallinity, decrease the HOMO level and enhance the stability. With lowering the HOMO level, more and more excellent and deep HOMO donor materials developed previously, can be used to match well with those small molecular acceptors for realizing much higher device performance. We will design different molecular structures of naphthopolyazacycle core, fused heterocycles with the naphthopolyazacycle core and terminal electron-deficient units for comprehensive regulation of optical absorption, energy level, charge transport, blend miscibility and crystallinity. This project will resolve the key scientific problems in molecular system of Y6. Subsequently, we will systematically study the binary blend and multiple blend devices based on our developed small molecular acceptor materials in this project. Finally, highly efficient tandem devices will be put forward and fabricated using above multiple blend cells as the sub-cells, which will break through the efficiency bottleneck of organic/polymer solar cells and establish foundation for realizing their commercial applications in the near future.