scholarly journals Alternative p-doped hole transport material for low operating voltage and high efficiency organic light-emitting diodes

2014 ◽  
Vol 105 (11) ◽  
pp. 113303 ◽  
Author(s):  
Caroline Murawski ◽  
Cornelius Fuchs ◽  
Simone Hofmann ◽  
Karl Leo ◽  
Malte C. Gather
Keyword(s):  
High Efficiency ◽  
Light Emitting Diodes ◽  
Hole Transport ◽  
Organic Light Emitting Diodes ◽  
Operating Voltage ◽  
Light Emitting ◽  
Organic Light

Efficient blue-green molecular organic light emitting diodes based on novel silole derivatives

2002 ◽  
Vol 725 ◽  
Author(s):  
Leonidas C. Palilis ◽  
Hideyuki Murata ◽  
Antti J. Mäkinen ◽  
Manabu Uchida ◽  
Zakya H. Kafafia
Keyword(s):  
Electron Transport ◽  
Quantum Efficiency ◽  
Light Emitting Diodes ◽  
Hole Transport ◽  
Organic Light Emitting Diodes ◽  
Operating Voltage ◽  
High Electron ◽  
Blue Fluorescence ◽  
Light Emitting ◽  
Organic Light

AbstractWe report on highly efficient molecular organic light-emitting diodes (MOLEDs) using two novel silole derivatives as emissive and electron transport materials. A silole derivative, namely 2,5-di-(3-biphenyl)-1,1-dimethyl-3,4-diphenylsilacyclopentadiene (PPSPP), which shows blue fluorescence with a high photoluminescence quantum yield of 85% in the solid state, was used as the emissive material. Another silole derivative, namely 2,5-bis-(2‘2“-bipyridin-6-yl)-1,1- dimethyl-3,4-diphenylsilacyclopentadiene (PyPySPyPy), that exhibits a non-dispersive high electron mobility of 2x10-4 cm2/Vsec was used as the electron transport material. MOLEDs using these two siloles and a common hole transport material show blue-green emission centered at 495 nm. This red-shifted electroluminescence (EL) band relative to the blue fluorescence of PPSPP is assigned to a PPSPP:NPB exciplex. A low operating voltage of 4.5 V was measured at a luminance of 100 cd/m2 and an EL quantum efficiency of 3.4% was achieved at 100 A/m2. To our knowledge, this is the highest EL quantum efficiency ever reported based on exciplex emission.

scholarly journals Effects of Charge Transport Materials on Blue Fluorescent Organic Light-Emitting Diodes with a Host-Dopant System

Micromachines ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 344 ◽  
Author(s):  
Neng Liu ◽  
Sijiong Mei ◽  
Dongwei Sun ◽  
Wuxing Shi ◽  
Jiahuan Feng ◽  
...  
Keyword(s):  
Electron Transport ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Molybdenum Trioxide ◽  
Hole Transport ◽  
Organic Light Emitting Diodes ◽  
Maximum Luminance ◽  
Light Emitting ◽  
Organic Light ◽  
Hole Transport Layers

High efficiency blue fluorescent organic light-emitting diodes (OLEDs), based on 1,3-bis(carbazol-9-yl)benzene (mCP) doped with 4,4’-bis(9-ethyl-3-carbazovinylene)-1,1’-biphenyl (BCzVBi), were fabricated using four different hole transport layers (HTLs) and two different electron transport layers (ETLs). Fixing the electron transport material TPBi, four hole transport materials, including 1,1-Bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC), N,N’-Di(1-naphthyl)-N,N’-diphenyl-(1,1’-biphenyl)-4’-diamine(NPB), 4,4’-Bis(N-carbazolyl)-1,1,-biphenyl (CBP) and molybdenum trioxide (MoO3), were selected to be HTLs, and the blue OLED with TAPC HTL exhibited a maximum luminance of 2955 cd/m2 and current efficiency (CE) of 5.75 cd/A at 50 mA/cm2, which are 68% and 62% higher, respectively, than those of the minimum values found in the device with MoO3 HTL. Fixing the hole transport material TAPC, the replacement of TPBi ETL with Bphen ETL can further improve the performance of the device, in which the maximum luminance can reach 3640 cd/m2 at 50 mA/cm2, which is 23% higher than that of the TPBi device. Furthermore, the lifetime of the device is also optimized by the change of ETL. These results indicate that the carrier mobility of transport materials and energy level alignment of different functional layers play important roles in the performance of the blue OLEDs. The findings suggest that selecting well-matched electron and hole transport materials is essential and beneficial for the device engineering of high-efficiency blue OLEDs.

High-efficiency, long-lifetime deep-blue organic light-emitting diodes

2021 ◽  
Vol 15 (3) ◽  
pp. 208-215 ◽  
Author(s):  
Soon Ok Jeon ◽  
Kyung Hyung Lee ◽  
Jong Soo Kim ◽  
Soo-Ghang Ihn ◽  
Yeon Sook Chung ◽  
...  
Keyword(s):  
High Efficiency ◽  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Deep Blue ◽  
Organic Light ◽  
Long Lifetime

scholarly journals High efficiency blue organic light-emitting diodes with below-bandgap electroluminescence

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Maria Vasilopoulou ◽  
Abd. Rashid bin Mohd Yusoff ◽  
Matyas Daboczi ◽  
Julio Conforto ◽  
Anderson Emanuel Ximim Gavim ◽  
...  
Keyword(s):  
High Efficiency ◽  
Light Emitting Diodes ◽  
High Mobility ◽  
Organic Light Emitting Diodes ◽  
Triplet Energy ◽  
Material Interface ◽  
Light Emitting ◽  
Thermally Activated ◽  
Organic Light ◽  
Hole Transporting

AbstractBlue organic light-emitting diodes require high triplet interlayer materials, which induce large energetic barriers at the interfaces resulting in high device voltages and reduced efficiencies. Here, we alleviate this issue by designing a low triplet energy hole transporting interlayer with high mobility, combined with an interface exciplex that confines excitons at the emissive layer/electron transporting material interface. As a result, blue thermally activated delay fluorescent organic light-emitting diodes with a below-bandgap turn-on voltage of 2.5 V and an external quantum efficiency (EQE) of 41.2% were successfully fabricated. These devices also showed suppressed efficiency roll-off maintaining an EQE of 34.8% at 1000 cd m−2. Our approach paves the way for further progress through exploring alternative device engineering approaches instead of only focusing on the demanding synthesis of organic compounds with complex structures.

scholarly journals Solution-Processed Efficient Blue Phosphorescent Organic Light-Emitting Diodes (PHOLEDs) Enabled by Hole-Transport Material Incorporated Single Emission Layer

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 554
Author(s):  
Taeshik Earmme
Keyword(s):  
Light Emitting Diodes ◽  
Blue Emission ◽  
Hole Transport ◽  
Organic Light Emitting Diodes ◽  
Emission Layer ◽  
Solution Processed ◽  
Light Emitting ◽  
Organic Light ◽  
Single Emission ◽  
Blue Phosphorescent

Solution-processed blue phosphorescent organic light-emitting diodes (PHOLEDs) based on a single emission layer with small-molecule hole-transport materials (HTMs) are demonstrated. Various HTMs have been readily incorporated by solution-processing to enhance hole-transport properties of the polymer-based emission layer. Poly(N-vinylcarbazole) (PVK)-based blue emission layer with iridium(III) bis(4,6-(di-fluorophenyl)pyridinato-N,C2′)picolinate (FIrpic) triplet emitter blended with solution-processed 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC) gave luminous efficiency of 21.1 cd/A at a brightness of 6220 cd/m2 with an external quantum efficiency (EQE) of 10.6%. Blue PHOLEDs with solution-incorporated HTMs turned out to be 50% more efficient compared to the reference device without HTMs. The high hole mobility, high triplet energy of HTM, and favorable energy transfer between HTM blended PVK host and FIrpic blue dopant were found to be important factors for achieving high device performance. The results are instructive to design and/or select proper hole-transport materials in solution-processed single emission layer.

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