9,9′-联芴烯衍生物在有机光伏电池中的应用

9,9′-Bifluorenylidene Derivatives for Organic Photovoltaic Cells

由于具有独特的14π电子芳香结构和扭曲的非平面构型,9,9′-联芴烯衍生物成为近年来被广泛研究的一类新型有机光伏材料。9,9′-联芴烯衍生物含有两个刚性平面内的联苯单元,因此具有良好的热稳定性和化学稳定性;且其具有优良的光电特性,很容易接受电子,从而提升自身的最低未占分子轨道(LUMO)能级,使得其有机光伏器件的开路电压增大。此外,9,9′-联芴烯有12个不同的取代位,与富勒烯衍生物相比,其结构更具灵活性。但是,该类化合物的电子迁移率较低,使得其光伏电池的光电转化效率过低。如何通过提高该类材料的电子迁移率、拓展其光谱吸收范围和吸收强度来提高光伏器件的光电转换效率,受到越来越多的关注和研究。阐述了近年来联芴烯衍生物在有机光伏电池中的研究进展,并对其结构、性能进行了简要的分析。最后,对联芴烯类材料的发展前景进行了展望。

As a new type of organic photovoltaic materials,9,9′-bifluorenylidene(9,9′-BF)derivatives have attracted much scientific attention due to the aromaticity and twisted structure of the 9,9′-bifluorenylidene core.9,9′-Bifluorenylidene derivatives contain two rigid coplane biphenyl units which can lead to good thermal and chemical stability of compounds,moreover,they have excellent photoelectric properties.These compounds could easily accept one electron to form 14-π-electron system,and thus they have aromaticity and improve the LUMO energy level of materials for increasing the open circuit voltage in organic photovoltaic(OPV)cells.In addition,9,9′-bifluorenylidene has 12 different substitution positions,they can be easily replaced by suitable groups to systhesize the needed molecules,and its structure is more flexible than fullerene derivatives.However,the bulk heterojunction organic photovoltaic cells based on the reported 9,9′-bifluorenylidene derivatives have lower power conversion efficiency(PCE)because of their lower electron mobility.The key issues for improving their electron mobility and spectral absorption in the UV-vis region have been attractive.In this paper,we review the recent advances on 9,9′-bifluorenylidene derivatives as organic optoelectronic functional materials in organic photovoltaic cells,and the performance of these materials is analyzed from the view of molecular structures.Finally,the prospect of the development of bifluorene-based materials is addressed.