Effect on Indium Zinc Oxide, Electron Transport and Hole Transport Materials for High Efficiency Blue Phosphorescent OLED

• Main Authors: Tzu-Chan Lin, 林資展
• Other Authors: Tien-Lung Chiu
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/grwv7q

碩士 === 元智大學 === 光電工程學系 === 104 === In this thesis, we studied the topic of high high-efficiency blue organic light-emitting diodes (OLEDs) using various hole transport layers (HTLs) and electron transport layers (ETLs) to adjust the carrier balance in the emitting layer. For host materials, hole-tranpsorting material, N,N’-dicarbazolyl-3,5-benzene (mCP), and electron-tranporting material 3-(4-Biphenylyl)-4-phenyl-5- tert-butylphenyl-1,2.4-triazole (TAZ) were employed in this study. Using four ETLs, e.g. TAZ, 1,3,5-tri(m-pyrid-3-yl-phenyl)benzene (TmPyPb), tris(2,4,6-triMethyl-3-(pyridin-3-yl)phenyl)borane (3TPyMb), diphenylbis(4-(pyridin-3-yl )phenyl )silane (DPPS), and two HTLs, e.g. N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)-benzidine (NPB), 1,1-Bis[4-[N,N-di(p-tolyl)amino]phenyl]cyclohexane (TAPC) to achieve the carrier balance, the OLEDs with TAZ and mCP host show distinct device performances, which could be deduced the carrier behavior of these ETLs, EMLs, and HTLs. For TAZ host device (TAPC HTL/TAZ ETL), the optimal device with ηc 48.57 cd/A, ηp 38.05 lm/W ηEQE 20.41 %； and for mCP device (TAPC HTL/DPPS ETL), the optimal device with ηc 54.43 cd/A, ηp 41.61 lm/W ηEQE 24.34 %. In addition, two new host materials, 9,9'-(2-(1-phenyl-1H-benzo[d]imidazol-2-yl)-1,3-phenylene)bis(9H-carbazole) (o-DiCbzBz) and 2,2'-bis(1-phenyl-1H-benzo[d]imidazol-2-yl)biphenyl (BImBP), offered from Prof. Man-kit Leung’s group at National Taiwan university chemistry. o-DiCbzBz and BImBP exhibited bipolar and electron-transporting behaviors, respectively. Using a partially mixing host to position at a part of EML, controlling their mixing ratio, and the thickness of this mixing layer, a high efficiency blue OLED could be obtained with current efficiency of 63.31 cd/A, power efficiency 61.26 lm/W, and external quantum efficiency of 28.22%. For the last study, a low temperature indium zinc oxide (IZO) was developed using radio frequence (RF) sputter. By adjusting the gas ratio between Ar and O2, substrate temperature, thickness of deposition layer, annealing temperature, an IZO with high transparency 88.1% at 450 –550 nm and high workfunction of 4.8 eV was obtained. OLED with IZO showed current efficiency of 49.78 cd/A, power efficiency 44.53 lm/W, and external quantum efficiency of 24.36%.