含氯原子的非富勒烯受体材料的分子工程与性能研究

It is quite a challenge in molecular engineering to design novel high-performance non-fullerene acceptors for higher power conversion efficiency: precisely elevate the LUMO level, improve the electron mobility and optical absorption ability of high-performance non-fullerene acceptors without hampering its morphological properties. Planar structure and electron-withdrawing groups are benefit for higher electron mobility. But these usually accompany with stronger aggregation and deeper LUMO level which are harmful to the performance of organic solar cells. In former study, applier discovered that chlorination can elevate the LUMO level and increase the molar extinction coefficiency. Additionally, adding chlorine atoms to conjugated cores is a general, effective route toward the design of n-type air-stable organic semiconductors. So the aim of this proposal is finding a way to enhance the photovoltaic performance of non-fullerene acceptors and simultaneously increase the short circuit current, open circuit voltage and fill factor of organic solar cells by chlorination of high-performance non-fullerene acceptors. Secondly, the unique structure-property relationship of chloride non-fullerene acceptors and the effects of chlorination on the key parameters of organic solar cells will be studied by introducing different number of chlorine or fluorine atoms onto various positions in a variety of non-fullerene acceptors.

为获得更高的光电转换效率，新型高效非富勒烯受体材料的分子工程面临严峻挑战：在保证与给体材料共混形成良好形貌的同时，需要具有良好的光吸收能力、较高的LUMO能级、更高的电子迁移率。更高的电子迁移率通常意味着更好的平面结构、更多的拉电子基团。这会导致材料的聚集和较深的LUMO能级，不利于器件效率的提升。申请人在前期的研究中发现氯原子可以提升材料的LUMO能级和摩尔消光系数。结合氯代被广泛用来提高材料电子迁移率的文献报道，本项目拟通过氯代进一步提升非富勒烯受体材料的光伏性能，有望同时提高有机太阳能电池的短路电流、开路电压和填充因子。本项目将在不同非富勒烯受体材料的不同位置引入不同数量的氯原子、氟原子，通过系统的比较，研究氯代对非富勒烯受体材料性能和有机太阳能电池关键参数的影响，揭示这种影响相对于氟代的特殊性。这一项目将为高效非富勒烯受体材料的开发提供新方法、新思路。

相比于氟代非富勒烯受体材料，氯代电子受体材料具有合成路线短、原料廉价易得的优势；但氯代非富勒烯受体材料的研究有待深入进行。本项目旨在设计合成新型的氯代非富勒烯受体材料，研究并揭示氯代位置和数量对非富勒烯受体材料吸光性能、能级结构、聚集行为、相分离行为和光伏性能的影响规律。本项目发现：（1）本项目首次报道了利用氯代非共轭结构修饰平面稠环类非富勒烯受体材料的方法。研究发现，在平面稠环类非富勒烯受体材料中，无论侧链氯代还是端基氯代，均能抑制非辐射复合造成的能量损失。通过优化非富勒烯受体材料的结构，氯代非富勒烯能够实现较低的能量损失，为高效费富勒烯受体材料的设计开发提供了新的工具。（2）氯代能够将异靛蓝类给体材料转变为电子受体材料。这一研究发现为设计新型电子受体材料提供了新的方法和途径。