Highly efficient inverted top emitting organic light emitting diodes using a horizontally oriented green phosphorescent emitter

Kim, Jung-Bum; Lee, Jeong‐Hwan; Moon, Chang‐Ki; Kim, Kwon‐Hyeon; Kim, Jang‐Joo

doi:10.1016/j.orgel.2014.08.004

Cited by 9 publications

(6 citation statements)

References 29 publications

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“…The optimized device was found to exhibit η ext of 27.6% at 1000 cd m –2 and CE of 120.7 cd A –1 , with reduced efficiency roll-off with EQE of 24.5% and luminous efficiency of 107.6 cd A –1 at 20,000 cd m –2 . Also, as predicted by simulation results, the device with 30 nm thick electron injection layer (EIL) was found to exhibit the highest luminance . Furthermore, in an endeavor to further simplify the devices based on the exciplex host systems, an electron-donor, TPAF with suitable HOMO was blended with the known electron-acceptor B3PYMPM and this was reported by Tao et al in 2017.…”

Section: Exciplex Forming Cohostsmentioning

confidence: 73%

Exciplex: An Intermolecular Charge-Transfer Approach for TADF

Sarma

Wong

2018

ACS Appl. Mater. Interfaces

335

260

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Organic materials that display thermally activated delayed fluorescence (TADF) are a striking class of functional materials that have witnessed a booming progress in recent years. In addition to pure TADF emitters achieved by the subtle manipulations of intramolecular charge transfer processes with sophisticated molecular structures, a new class of efficient TADF-based OLEDs with emitting layer formed by blending electron donor and acceptor molecules that involve intermolecular charge transfer have also been fabricated. In contrast to pure TADF materials, the exciplex-based systems can realize small Δ E (0-0.05 eV) much more easily since the electron and hole are positioned on two different molecules, thereby giving small exchange energy. Consequently, exciplex-based OLEDs have the prospective to maximize the TADF contribution and achieve theoretical 100% internal quantum efficiency. Therefore, the challenging issue of achieving small Δ E in organic systems could be solved. In this article, we summarize and discuss the latest and most significant developments regarding these rapidly evolving functional materials, wherein the majority of the reported exciplex forming systems are categorized into two subgroups, viz. (a) exciplex as TADF emitters and (b) those as hosts for fluorescent, phosphorescent and TADF dopants according to their structural features and applications. The working mechanisms of the direct electroluminescence from the donor/acceptor interface and the exciplex-forming systems as cohost for the realization of high efficiency OLEDs are reviewed and discussed. This article delivers a summary of the current progresses and achievements of exciplex-based researches and points out the future challenges to trigger more research endeavors to this growing field.

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Section: Exciplex Forming Cohostsmentioning

confidence: 73%

Exciplex: An Intermolecular Charge-Transfer Approach for TADF

Sarma

Wong

2018

ACS Appl. Mater. Interfaces

335

260

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“…Thereafter, the search began for other iridium complexes exhibiting nonisotropic alignment of their TDMVs. As a consequence, several other molecules were found to display behavior similar to IrðmdqÞ 2 ðacacÞ, and the importance to light outcoupling was demonstrated [81,86,87,[209][210][211][212][213][214][215][216][217][218]. Using the feature of predominantly horizontal alignment of the TDMVs of such Ir complexes subsequently allowed OLED efficiencies for direct…”

Section: Iridium Complexes Exhibiting Deviations From Isotropymentioning

confidence: 99%

Emitter Orientation as a Key Parameter in Organic Light-Emitting Diodes

et al. 2017

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The distinct preferential alignment, i.e., horizontal orientation with respect to the substrate plane, of the optical transition dipole moment vectors (TDMVs) of organic dye molecules is of paramount importance for extracting the internally generated power of organic light-emitting diodes (OLEDs) to the outside world. This feature is one of the most promising approaches for the enhancement of the electrical efficacy in stateof-the-art OLEDs, as their internal quantum efficiencies are already close to the ultimate limit. If one can achieve complete horizontal orientation of the TDMVs, it is possible to increase the efficiency by at least 50% because alignment strongly influences the power dissipation into the different optical modes present in such a thin-film device. Thus, this feature of organic light-emitting molecules can lead to advanced performance for future applications. Therefore, we present here a review of recent achievements, ongoing research, and future tasks in this particular area of organic electronics.

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“…In addition, an expected half-lifetime of over 10,000 h from an initial luminance of 1,000 cd/m 2 was demonstrated by employing compound B as the EIL. Although there have recently been many reports on efficient iOLEDs [4,5,[7][8][9][10][11][12][13], an iOLED with high operational stability has never been reported. This is the first demonstration of an efficient and operationally stable iOLED.…”

Section: Resultsmentioning

confidence: 99%

“…We previously demonstrated that a highly efficient and relatively air-stable iOLED can be realized by employing a zinc oxide (ZnO)/poly(ethylene imine) (PEI) stacked layer as an EIL [6][7][8][9]. In addition, several highly efficient iOLEDs have recently been reported that employ not only PEI but also chemically doped organic layers [10][11][12][13]. However, the effects of such organic EILs on the operational and storage stability of iOLEDs have not been discussed.…”

Section: Introductionmentioning

confidence: 99%