Sub‐Picosecond Singlet Exciton Fission in Cyano‐Substituted Diaryltetracenes |
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Authors: | Eric A. Margulies Dr. Yi‐Lin Wu Przemyslaw Gawel Dr. Stephen A. Miller Dr. Leah E. Shoer Prof. Dr. Richard D. Schaller Prof. Dr. François Diederich Prof. Dr. Michael R. Wasielewski |
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Affiliation: | 1. Department of Chemistry and Argonne‐Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (USA);2. Laboratorium für Organische Chemie, ETH Zürich, Vladimir‐Prelog‐Weg 3, HCI, 8093 Zürich (Switzerland);3. Department of Chemistry, Northwestern University and Center for Nanoscale Materials, Argonne National Laboratory, Argonne, IL 60439 (USA) |
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Abstract: | Thin films of 5,11‐dicyano‐6,12‐diphenyltetracene ( TcCN ) have been studied for their ability to undergo singlet exciton fission (SF). Functionalization of tetracene with cyano substituents yields a more stable chromophore with favorable energetics for exoergic SF (2E(T1)?E(S1)=?0.17 eV), where S1 and T1 are singlet and triplet excitons, respectively. As a result of tuning the triplet‐state energy, SF is faster in TcCN relative to the corresponding endoergic process in tetracene. SF proceeds with two time constants in the film samples (τ=0.8±0.2 ps and τ=23±3 ps), which is attributed to structural disorder within the film giving rise to one population with a favorable interchromophore geometry, which undergoes rapid SF, and a second population in which the initially formed singlet exciton must diffuse to a site at which this favorable geometry exists. A triplet yield analysis using transient absorption spectra indicates the formation of 1.6±0.3 triplets per initial excited state. |
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Keywords: | chromophores photophysics singlet fission tetracene derivatives time‐resolved spectroscopy |
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