Effect of dielectric character of electron transporting materials on the performance of organic light-emitting diodes

MRS Advances ◽  
2018 ◽  
Vol 3 (59) ◽  
pp. 3445-3451 ◽  
Author(s):  
Rohit Ashok Kumar Yadav ◽  
Deepak Kumar Dubey ◽  
Sun-Zen Chen ◽  
Sujith Sudheendran Swayamprabha ◽  
Tzu-Wei Liang ◽  
...  

AbstractOrganic light-emitting diodes (OLEDs) have progressively attracted generous attention because of their versatile applications in solid state lighting and full color displays. High-efficiency is crucial for OLED devices being energy saving and to have a longer lifespan. Numerous approaches have been attempted to attain high-efficiency OLEDs via newly synthesized organic materials, light-extraction structure design and energy-efficient device architectures. The organic materials used in optoelectronic devices have inherently low dielectric constant. In this work, we demonstrate a comprehensive model to quantitatively investigate the role of dielectric constant of the electron transporting material on the electric field distribution, charge drift and exciton recombination probability across the emissive layer (EML) and electron transport layer (ETL) in organic light-emitting diode via commercialized electrical simulation package SETFOS.

2017 ◽  
Vol 5 (12) ◽  
pp. 3097-3106 ◽  
Author(s):  
Jin-Hoon Kim ◽  
Jin-Woo Park

When using PEIE doped with n-type dopants as the ETL, ϕ of the cathode decreased, significantly improving OLED performance.


2012 ◽  
Vol 629 ◽  
pp. 224-228 ◽  
Author(s):  
Kwang Sik Kim ◽  
Young Wook Hwang ◽  
Tae Young Won

We report our finite element method (FEM) simulation study on the characteristic of the charge transport layer of the multi-layer structure for organic light emitting diodes (OLEDs). The physical model cover all the key physical processes in OLEDs, namely charge injection, transport and recombination, exciton diffusion, transfer and decay for electronic properties. We performed a numerical simulation on a multilayer structure comprising a hole transport layer (HTL), an emission layer (EML), and an electron transport layer (ETL) between both electrodes; anode and cathode. The materials of the HTL is TPD (N, N'-Bis (3- methylphenyl) - N, N'- bis (phenyl) benzidine), and the ETL includes Alq3 (Tris (8- hyroxyquinolinato) aluminium). Here, we investigated the parameters such as recombination rates which influence the efficiency of the charge transport between layers in bilayer OLEDs. We also analyzed a transient response during the turn on period and the carrier transport in accordance with the variation of the injection barrier and applied voltage. In addition, this paper revealed that the effect of the insertion of the EML in bilayer structure.


2016 ◽  
Vol 16 (4) ◽  
pp. 3368-3372 ◽  
Author(s):  
Shuri Sato ◽  
Masashi Takata ◽  
Makoto Takada ◽  
Hiroyoshi Naito

The degradation of bilayer organic light-emitting diodes (OLEDs) with a device structure of N, N′-di(1-naphthyl)-N, N′-diphenylbenzidine (α-NPD) (hole transport layer) and tris-(8-hydroxyquinolate)aluminum (Alq3) (emissive layer and electron transport layer) has been studied by impedance spectroscopy and device simulation. Two modulus peaks are found in the modulus spectra of the OLEDs below the electroluminescence threshold. After aging of the OLEDs, the intensity of electroluminescence is degraded and the modulus peak due to the Alq3 layer is shifted to lower frequency, indicating that the resistance of the Alq3 layer is increased. Device simulation reveals that the increase in the resistance of the Alq3 layer is due to the decrease in the electron mobility in the Alq3 layer.


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