Exciton efficiency beyond the spin statistical limit in organic light emitting diodes based on anthracene derivatives

Nidhi Sharma, Michael Yin Wong, David Hall, Eduard Spuling, Francisco Tenopala Carmona, Alberto Privitera, Graeme Jeffrey Copley, David Bradford Cordes, Alexandra Martha Zoya Slawin, Caroline Murawski, Malte Christian Gather, David Beljonne, Yoann Olivier, Ifor D. W. Samuel, Eli Zysman-Colman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)
21 Downloads (Pure)

Abstract

We report two donor-acceptor (D-A) materials based on a cyanoanthracene acceptor paired with diphenylamine (DPAAnCN) and carbazole (CzAnCN) donor moieties. These compounds show hybrid locally excited (LE) charge-transfer (CT) excited states (HLCT), which we demonstrated through a combined photophysical and computational study. Vacuum- deposited organic light emitting diodes (OLEDs) using these HLCT emitters exhibit maximum external quantum efficiencies (EQEmax) close to 6%, with impressive exciton utilization efficiency (Φs) of >50%, far exceeding the spin statistic limit of 25%. We rule out triplet-triplet annihilation and thermally activated delayed fluorescence as triplet harvesting mechanisms along with horizontal orientation of emitters to enhance light outcoupling and, instead, propose a “hot exciton” channel involving the nearly isoenergetic T2 and S1 states.
Original languageEnglish
JournalJournal of Materials Chemistry C
VolumeIn press
Early online date28 Jan 2020
DOIs
Publication statusE-pub ahead of print - 28 Jan 2020

Fingerprint

Dive into the research topics of 'Exciton efficiency beyond the spin statistical limit in organic light emitting diodes based on anthracene derivatives'. Together they form a unique fingerprint.

Cite this