Peinkofer Kathryn R, Williams Malik L, Mantel Georgia C, Phelan Brian T, Young Ryan M, Wasielewski Michael R
Department of Chemistry and Paula M. Trienens Institute for Sustainability and Energy, Northwestern University, Evanston, Illinois 60208-3113, United States.
J Am Chem Soc. 2024 Dec 18;146(50):34934-34942. doi: 10.1021/jacs.4c14550. Epub 2024 Dec 10.
Singlet exciton fission (SF) and symmetry-breaking charge separation (SB-CS) are both photophysical processes that can occur between two organic chromophores and are both of interest to improve solar energy conversion. Here, we tuned the photophysics of a 9,9'-bianthracene () single crystal between SF and SB-CS using solvent intercalation to change the electric field within the crystal. Crystals of were grown in -xylene, chlorobenzene, -dichlorobenzene, and benzonitrile, as well as solvent-free from a melt. The crystals were studied by X-ray diffraction, steady-state optical spectroscopy, and transient absorption microscopy to elucidate the role of the intercalated solvent molecules. The crystals with no solvent in the structure undergo fast SF (<2 ps), while the crystals with intercalated moderately polar solvents -xylene, chlorobenzene, and -dichlorobenzene show evidence of charge-transfer-mediated SF. Finally, the crystals containing highly polar benzonitrile undergo SB-CS instead of SF. These results demonstrate that controlling solvation of in the crystal structure can tune its photophysics between SF and SB-CS.
单线态激子裂变（SF）和对称破缺电荷分离（SB-CS）都是可能发生在两个有机发色团之间的光物理过程，并且二者对于改善太阳能转换都具有重要意义。在此，我们通过溶剂插层来改变晶体内部的电场，从而在SF和SB-CS之间调节9,9'-联蒽单晶的光物理性质。9,9'-联蒽的晶体在对二甲苯、氯苯、邻二氯苯和苯甲腈中生长，以及在无溶剂条件下从熔体中生长。通过X射线衍射、稳态光谱学和瞬态吸收显微镜对晶体进行研究，以阐明插层溶剂分子的作用。结构中无溶剂的晶体经历快速的SF（<2皮秒），而插层有中等极性溶剂对二甲苯、氯苯和邻二氯苯的晶体显示出电荷转移介导的SF的证据。最后，含有高极性苯甲腈的晶体发生SB-CS而非SF。这些结果表明，控制9,9'-联蒽在晶体结构中的溶剂化作用可以在SF和SB-CS之间调节其光物理性质。
