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Title: High performance blue-emitting organic light-emitting diodes from thermally activated delayed fluorescence: A guest/host ratio study

Abstract

Emitters displaying thermally activated delayed fluorescence (TADF) can lead to highly efficient organic light-emitting diodes (OLEDs). Such emitters are usually incorporated into the emissive layer (EML) at a relatively low concentration (< 20 wt. %) with respect to a host material, a guest-host approach inherited from conventional fluorescent or phosphorescent OLEDs. Here, detailed studies on OLEDs, in which the concentration of oBFCzTrz (a blue-emitter displaying TADF) in a DPEPO host was varied from 8 to 100 wt. %, reveals that oBFCzTrz displays ambipolar transport and limited fluorescence-quenching due to aggregation. For instance, a neat film of oBFCzTrz maintains a photoluminescence quantum yield of 82%. We demonstrate that OLEDs with an EML having an oBFCzTrz concentration of 50 wt. % in DPEPO yield a maximum external quantum efficiency (EQE) of 25.5% with an EQE roll-off of 10% in the range from 10 to 1,000 cd/m2 and Commission Internationale de l’Eclairage color coordinates of (0.20, 0.44). OLEDs with smaller or larger oBFCzTrz concentrations display smaller maximum EQE values. OLEDs with a neat oBFCzTrz EML display a maximum EQE of 14.0%. Time-resolved electroluminescent decay studies, and analysis using a simple model, reveal significant differences in transport, trapping, and recombination in these devices.

Authors:
 [1];  [1];  [1];  [1];  [1];  [1]; ORCiD logo [1]
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  1. Georgia Inst. of Technology, Atlanta, GA (United States)
Publication Date:
Research Org.:
Georgia Institute of Technology, Atlanta, GA (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1540237
Alternate Identifier(s):
OSTI ID: 1463225; OSTI ID: 1767166
Grant/Contract Number:  
EE0008205
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 124; Journal Issue: 5; Journal ID: ISSN 0021-8979
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; 36 MATERIALS SCIENCE; Excitons; Photoluminescence; Quantum efficiency; Fluorescence quenching; Light emitting diodes; Electric currents; Charge transport; Polarons; Solid state lighting, Organic light-emitting diodes

Citation Formats

Zhang, Xiaoqing, Fuentes-Hernandez, Canek, Zhang, Yadong, Cooper, Matthew W., Barlow, Stephen, Marder, Seth R., and Kippelen, Bernard. High performance blue-emitting organic light-emitting diodes from thermally activated delayed fluorescence: A guest/host ratio study. United States: N. p., 2018. Web. doi:10.1063/1.5041447.
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Zhang, Xiaoqing, Fuentes-Hernandez, Canek, Zhang, Yadong, Cooper, Matthew W., Barlow, Stephen, Marder, Seth R., & Kippelen, Bernard. High performance blue-emitting organic light-emitting diodes from thermally activated delayed fluorescence: A guest/host ratio study. United States. doi:https://doi.org/10.1063/1.5041447
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Zhang, Xiaoqing, Fuentes-Hernandez, Canek, Zhang, Yadong, Cooper, Matthew W., Barlow, Stephen, Marder, Seth R., and Kippelen, Bernard. Tue . "High performance blue-emitting organic light-emitting diodes from thermally activated delayed fluorescence: A guest/host ratio study". United States. doi:https://doi.org/10.1063/1.5041447. https://www.osti.gov/servlets/purl/1540237.
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@article{osti_1540237,
title = {High performance blue-emitting organic light-emitting diodes from thermally activated delayed fluorescence: A guest/host ratio study},
author = {Zhang, Xiaoqing and Fuentes-Hernandez, Canek and Zhang, Yadong and Cooper, Matthew W. and Barlow, Stephen and Marder, Seth R. and Kippelen, Bernard},
abstractNote = {Emitters displaying thermally activated delayed fluorescence (TADF) can lead to highly efficient organic light-emitting diodes (OLEDs). Such emitters are usually incorporated into the emissive layer (EML) at a relatively low concentration (< 20 wt. %) with respect to a host material, a guest-host approach inherited from conventional fluorescent or phosphorescent OLEDs. Here, detailed studies on OLEDs, in which the concentration of oBFCzTrz (a blue-emitter displaying TADF) in a DPEPO host was varied from 8 to 100 wt. %, reveals that oBFCzTrz displays ambipolar transport and limited fluorescence-quenching due to aggregation. For instance, a neat film of oBFCzTrz maintains a photoluminescence quantum yield of 82%. We demonstrate that OLEDs with an EML having an oBFCzTrz concentration of 50 wt. % in DPEPO yield a maximum external quantum efficiency (EQE) of 25.5% with an EQE roll-off of 10% in the range from 10 to 1,000 cd/m2 and Commission Internationale de l’Eclairage color coordinates of (0.20, 0.44). OLEDs with smaller or larger oBFCzTrz concentrations display smaller maximum EQE values. OLEDs with a neat oBFCzTrz EML display a maximum EQE of 14.0%. Time-resolved electroluminescent decay studies, and analysis using a simple model, reveal significant differences in transport, trapping, and recombination in these devices.},
doi = {10.1063/1.5041447},
journal = {Journal of Applied Physics},
number = 5,
volume = 124,
place = {United States},
year = {2018},
month = {8}
}
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DOI:  https://doi.org/10.1063/1.5041447
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