Direct Observation of a Charge-Transfer State Preceding High-Yield Singlet Fission in Terrylenediimide Thin Films

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• 作者：Eric A. Margulies ; Jenna L. Logsdon ; Claire E. Miller ; Lin Ma ; Ethan Simonoff ; Ryan M. YoungGeorge C. Schatz ; Michael R. Wasielewski
• 刊名：Journal of the American Chemical Society
• 出版年：2017
• 出版时间：January 18, 2017
• 年：2017
• 卷：139
• 期：2
• 页码：663-671
• 全文大小：658K
• ISSN：1520-5126

文摘

Singlet exciton fission (SF) in organic chromophore assemblies results in the conversion of one singlet exciton (S₁) into two triplet excitons (T₁), provided that the overall process is exoergic, i.e., E(S₁) > 2E(T₁). We report on SF in thin polycrystalline films of two terrylene-3,4:11,12-bis(dicarboximide) (TDI) derivatives 1 and 2, which crystallize into two distinct π-stacked structures. Femtosecond transient absorption spectroscopy (fsTA) reveals a charge-transfer state preceding a 190% T₁ yield in films of 1, where the π-stacked TDI molecules are rotated by 23° along an axis perpendicular to their π systems. In contrast, when the TDI molecules are slip-stacked along their N–N axes in films of 2, fsTA shows excimer formation, followed by a 50% T₁ yield.