Improving the Stability of Organic Semiconductors: Distortion Energy versus Aromaticity in Substituted Bistetracene

Simil Thomas, Jack Ly, Lei Zhang, Alejandro L. Briseno, Jean-Luc Bredas

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Polycyclic aromatic hydrocarbons (PAHs) have been widely explored as molecular semiconductors in organic electronic devices such as field-effect transistors or solar cells. However, their tendency to undergo photooxidation is a primary limitation to their practical applications. Bistetracene derivatives have recently been demonstrated to possess much larger photo oxidation stability than the widely investigated pentacene and rubrene, while maintaining high charge-carrier mobilities. Here, using several levels of density functional theory, we identify the origin of the increased stability of bistetracene with respect to molecular oxygen by systematically investigating the [4 + 2] cycloaddition (Diels Alder) photooxidation reaction mechanism. Importantly, our computational results indicate that endoperoxide formation in bis(2-(trimethylsilyl)ethynyl) bistetracene (BT) occurs not on the ring with least aromaticity, but rather on the ring with smallest distortion energy. This feature was subsequently confirmed by experimental NMR analyses. The oxidation activation barriers of bistetracene, pentacene, and rubrene are found to be 17.7, 13.6, and 14.4 kcal/mol, respectively, in agreement with the observed order of stability of these molecules with respect to oxidation reactions in solution. In the cases of BT and pentacene, the rates of electron transfer to create charged species (PAH(+) and O-2) are at least two orders of magnitude lower than that of the charge recombination process (back to PAH and O-2); for rubrene, both of these processes are calculated to be of the same order of magnitude, in agreement with experimental electron paramagnetic resonance spectroscopy observations.
Original languageEnglish (US)
Pages (from-to)8504-8512
Number of pages9
JournalChemistry of Materials
Volume28
Issue number23
DOIs
StatePublished - Nov 28 2016

Fingerprint Dive into the research topics of 'Improving the Stability of Organic Semiconductors: Distortion Energy versus Aromaticity in Substituted Bistetracene'. Together they form a unique fingerprint.

Cite this