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Modulating the Electronic and Solid‐State Structure of Organic Semiconductors by Site‐Specific Substitution: The Case of Tetrafluoropentacenes
Author(s) -
Geiger Thomas,
Schundelmeier Simon,
Hummel Thorsten,
Ströbele Markus,
Leis Wolfgang,
Seitz Michael,
Zeiser Clemens,
Moretti Luca,
Maiuri Margherita,
Cerullo Giulio,
Broch Katharina,
Vahland Jörn,
Leo Karl,
MaichleMössmer Cäcilia,
Speiser Bernd,
Bettinger Holger F.
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201905843
Subject(s) - pentacene , organic field effect transistor , crystallography , acene , chemistry , organic semiconductor , stacking , crystal structure , materials science , thin film transistor , molecule , transistor , field effect transistor , organic chemistry , physics , electrode , voltage , quantum mechanics
The properties as well as solid‐state structures, singlet fission, and organic field‐effect transistor (OFET) performance of three tetrafluoropentacenes (1,4,8,11: 10 , 1,4,9,10: 11 , 2,3,9,10: 12 ) are compared herein. The novel compounds 10 and 11 were synthesized in high purity from the corresponding 6,13‐etheno‐bridged precursors by reaction with dimethyl 1,2,4,5‐tetrazine‐3,6‐dicarboxylate at elevated temperatures. Although most of the molecular properties of the compounds are similar, their chemical reactivity and crystal structures differ considerably. Isomer 10 undergoes the orbital symmetry forbidden thermal [4+4] dimerization, whereas 11 and 12 are much less reactive. The isomers 11 and 12 crystallize in a herringbone motif, but 10 prefers π–π stacking. Although the energy of the first electric dipole‐allowed optical transition varies only within 370 cm −1 (0.05 eV) for the neutral compounds, this amounts to roughly 1600 cm −1 (0.20 eV) for radical cations and 1300 cm −1 (0.16 eV) for dications. Transient spectroscopy of films of 11 and 12 reveals singlet‐fission time constants (91±11, 73±3 fs, respectively) that are shorter than for pentacene (112±9 fs). OFET devices constructed from 11 and 12 show close to ideal thin‐film transistor (TFT) characteristics with electron mobilities of 2×10 −3 and 6×10 −2 cm 2 V −1 s −1 , respectively.