Abstract
The realization of a deep-blue-emitting exciplex system is a herculean task in the field of organic light-emitting diodes (OLEDs) on account of a large red-shifted and broadened exciplex emission spectrum in comparison to those of the corresponding single compounds. Herein, 2,5,8-tris(di(4-fluorophenyl)amine)-1,3,4,6,7,9,9b-heptaazaphenalene (HAP-3FDPA) was designed as an electron acceptor by integrating three bis(4-fluorophenyl)amine groups into a heptazine core, while 1,3-di(9H-carbazol-9-yl)benzene (mCP) possessing two electron-donating carbazole moieties was chosen as the electron donor. Excitingly, the exciplex system of 8 wt% HAP-3FDPA:mCP exhibited deep-blue emission and a high photoluminescence quantum yield of 53.2%. More importantly, an OLED containing this exciplex system as an emitting layer showed deep-blue emission with Commission Internationale de l’Eclairage coordinates of (0.16, 0.12), a peak luminance of 15,148 cd m−2, and a rather high maximum external quantum efficiency of 10.2% along with a low roll-off. This study not only reports an efficient exciplex-based deep-blue emitter but also presents a feasible pathway to construct highly efficient deep-blue OLEDs based on exciplex systems.
Highlights
To realize a small ∆EST, effective separation of electron densities of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) is indispensable because the ∆EST is proportional to the exchange integrals between the wave functions of the HOMO and LUMO [9]
In 2012 by Adachi et al [16], a large number of exciplex-based emitters developed, whereas a majority of them exhibit green, yellow, exciplex or red. In have this been study, we developed an efficient deep‐blue‐emitting sys emission because exciplex formation is usually accompanied by a large red-shift and a employing 2,5,8‐tris(di(4‐fluorophenyl)amine)‐1,3,4,6,7,9,9b‐heptaazaphenalene
We developed an efficient exciplex systemmoieties employingis a wid used host material and was chosen as an electron donor to form exciplex
Summary
Organic light-emitting diodes (OLEDs) based on thermally activated delayed fluorescent (TADF) emitters have obtained considerable progress over the last decade [1,2,3,4,5]. In 2012 by Adachi et al [16], a large number of exciplex-based emitters developed, whereas a majority of them exhibit green, yellow, exciplex or red In have this been study, we developed an efficient deep‐blue‐emitting sys emission because exciplex formation is usually accompanied by a large red-shift and a employing 2,5,8‐tris(di(4‐fluorophenyl)amine)‐1,3,4,6,7,9,9b‐heptaazaphenalene HAP‐3FDPA, which is compose blue emitters are quite difficult to acquire and in urgent need of exciplex-based full-color adisplays heptazine core and three bis(4‐fluorophenyl)amine groups, was designed as an elect or white-light OLEDs. In thiswhile study, we developed an efficient exciplex systemmoieties employingis a wid used host material [21]. A rather high maximum external quantum efficiency (EQE) of 10.2% along with a fairly
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