A1 Refereed original research article in a scientific journal
Insights into Charge Transport in High-Efficiency Green Solution-Processed Thermally Activated Delayed Fluorescence Organic Light-Emitting Diodes with a Single Emitting Layer
Authors: Kumar M, Chapran M, Wiosna-Salyga G, Sleczkowski P, Luszczynska B, Pereira L
Publisher: AMER CHEMICAL SOC
Publication year: 2020
Journal: Journal of Physical Chemistry C
Journal name in source: JOURNAL OF PHYSICAL CHEMISTRY C
Journal acronym: J PHYS CHEM C
Volume: 124
First page : 21935
Last page: 21947
Number of pages: 13
ISSN: 1932-7447
DOI: https://doi.org/10.1021/acs.jpcc.0c04938
Abstract
Simple solution-processed structures of organic light-emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) have been demonstrated, but their efficiency and roll-off are still problematic, mainly due to the difficulty in optimizing such device structures. For the first time, solution-processed fabrication of efficient TADF green OLEDs with a simple structure is demonstrated. The emitter 2PXZ-OXD (2,5-bis(4-(10H-phenoxazin-10-yl)phenyl)-1,3,4-oxadiazole) was dispersed in a poly(N-vinylcarbazole)/1,3-bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazo- 5-yl]benzene (OXD-7) host matrix. Different emitter concentrations (1-10% wt) and different layer thicknesses were applied. Photophysical analysis supports the device structure configuration. The results show a balanced electrical carrier transport, a low turn-on voltage (5 V), an external quantum efficiency (EQE) of 7.5%, and a current efficiency of 16.2 cd/A with a brightness of 7240 cd/m(2). The device exhibited a suppressed roll-off at 1000 cd/m(2) (EQE: 7.15%). Simulations of charge transport properties allowed to explain the results and to optimize, opening interesting frameworks for simple solution-deposited large-area OLEDs.
Simple solution-processed structures of organic light-emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) have been demonstrated, but their efficiency and roll-off are still problematic, mainly due to the difficulty in optimizing such device structures. For the first time, solution-processed fabrication of efficient TADF green OLEDs with a simple structure is demonstrated. The emitter 2PXZ-OXD (2,5-bis(4-(10H-phenoxazin-10-yl)phenyl)-1,3,4-oxadiazole) was dispersed in a poly(N-vinylcarbazole)/1,3-bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazo- 5-yl]benzene (OXD-7) host matrix. Different emitter concentrations (1-10% wt) and different layer thicknesses were applied. Photophysical analysis supports the device structure configuration. The results show a balanced electrical carrier transport, a low turn-on voltage (5 V), an external quantum efficiency (EQE) of 7.5%, and a current efficiency of 16.2 cd/A with a brightness of 7240 cd/m(2). The device exhibited a suppressed roll-off at 1000 cd/m(2) (EQE: 7.15%). Simulations of charge transport properties allowed to explain the results and to optimize, opening interesting frameworks for simple solution-deposited large-area OLEDs.
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