TY - JOUR
T1 - Exciton efficiency beyond the spin statistical limit in organic light emitting diodes based on anthracene derivatives
AU - Sharma, Nidhi
AU - Wong, Michael Yin
AU - Hall, David
AU - Spuling, Eduard
AU - Tenopala Carmona, Francisco
AU - Privitera, Alberto
AU - Copley, Graeme Jeffrey
AU - Cordes, David Bradford
AU - Slawin, Alexandra Martha Zoya
AU - Murawski, Caroline
AU - Gather, Malte Christian
AU - Beljonne, David
AU - Olivier, Yoann
AU - Samuel, Ifor D. W.
AU - Zysman-Colman, Eli
N1 - E.Z.-C. acknowledges the University of St Andrews and the Leverhulme Trust (RPG- 2016-047) for financial support. E.Z.-C. and I.D.W.S. thank EPSRC (EP/P010482/1) for support. We thank EPSRC UK National Mass Spectrometry Facility at Swansea University for analytical services. The work in Mons was supported by the European Union’s Horizon 2020 research and innovation program under Grant Agreement N°. 646176 (EXTMOS project). Computational resources have been provided by the Consortium des Équipements de Calcul Intensif (CÉCI), funded by the Fonds de la Recherche Scientifiques de Belgique (F.R.S.- FNRS) under Grant No. 2.5020.11. C.M. and G.C acknowledge funding by the European Commission through a Marie Skłodowska Curie fellowship (No. 703387 and 799302, respectively). M.C.G. acknowledges funding from EPSRC (EP/R010595/1). A.P. acknowledges the European Union’s Horizon 2020 research and innovation programme under Marie Sklodowska Curie Grant agreement No. 722651 (SEPOMO project). EPR measurements were performed in the Centre for Advanced ESR (CAESR), located in the Department of Chemistry of the University of Oxford, and this work was supported by the EPSRC (EP/L011972/1).
PY - 2020/3/21
Y1 - 2020/3/21
N2 - 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.
AB - 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.
U2 - 10.1039/C9TC06356K
DO - 10.1039/C9TC06356K
M3 - Article
SN - 2050-7526
VL - 8
SP - 3773
EP - 3783
JO - Journal of Materials Chemistry C
JF - Journal of Materials Chemistry C
IS - 11
ER -