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2019-09-23 - Welch - ChemRxiv - Th4PDI4.pdf (4.01 MB)

Harnessing Direct(Hetero)Arylation in Pursuit of a Saddle-Shaped Perylene Diimide Tetramer

preprint
submitted on 23.09.2019, 19:14 and posted on 27.09.2019, 16:24 by Joshua Koenig, Audrey Laventure, Gregory Welch

This contribution explores the direct(hetero) arylation (DHA) cross-coupling of a saddle-like, π-conjugated cyclooctatetrathiophene (Th4) core with the N-annulated perylene diimide (PDI) chromophore. Replacing the bulky pivalic acid with acetic acid enabled a facile cross-coupling, selectively forming a PDI tetramer (Th4PDI4) in a 70% overall yield. The optoelectronic properties of Th4PDI4 were characterized and density functional theory (DFT) was used to calculate the optimized molecular geometry and molecular orbitals (MOs). MOs determined by cyclic voltammetry corresponded well with those calculated using DFT. The molecular geometry calculated by DFT showed Th4PDI4 adopts two separate PDI-PDI conformations (propeller and double-decker). Organic photovoltaic (OPV) devices were fabricated using a blend of PTB7-Th:Th4PDI4, where an initial power conversion efficiency (PCE) of 1.89 % was improved by testing a series of solvent additives and thermal annealing techniques. Through use of 3 % (v/v) 1-chloronaphthalene additive, a combination of higher short circuit current (Jsc = 10.2 mA/cm2) and fill factor (FF = 42 %) led to an overall increase in PCE to 4.26 %.

Funding

NSERC Discovery Grant 2019-04392

History

Email Address of Submitting Author

gregory.welch@ucalgary.ca

Institution

University of Calgary

Country

Canada

ORCID For Submitting Author

0000-0002-3768-937X

Declaration of Conflict of Interest

None

Version Notes

Version One

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