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Sub‐Picosecond Singlet Exciton Fission in Cyano‐Substituted Diaryltetracenes
Author(s) -
Margulies Eric A.,
Wu YiLin,
Gawel Przemyslaw,
Miller Stephen A.,
Shoer Leah E.,
Schaller Richard D.,
Diederich François,
Wasielewski Michael R.
Publication year - 2015
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201501355
Subject(s) - tetracene , singlet fission , chemistry , singlet state , chromophore , exciton , photochemistry , excited state , picosecond , population , triplet state , atomic physics , anthracene , physics , optics , demography , laser , sociology , quantum mechanics
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(T 1 )−E(S 1 )=−0.17 eV), where S 1 and T 1 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.