Balancing Charge Injection and Transport in Organic Light-emitting Diodes with a Transparent Conductive Tungsten Oxide Layer

2014 ◽  
Vol 1629 ◽  
Author(s):  
R. Acharya ◽  
X. M. Li ◽  
Y. Lu ◽  
X. A. Cao
Keyword(s):  
Current Efficiency ◽  
Light Emitting Diodes ◽  
Charge Injection ◽  
Hole Transport ◽  
Organic Light Emitting Diodes ◽  
Transport Layer ◽  
Hole Injection ◽  
Hole Transport Layer ◽  
Light Emitting ◽  
Organic Light

ABSTRACTHigh-brightness green phosphorescent hybrid inorganic-organic light-emitting diodes (HyLEDs) and inverted HyLEDs (IHyLEDs) have been demonstrated. The devices comprised a transparent and conductive WO3 layer deposited by thermal evaporation, which improved both hole injection and transport, and led to more balanced charge injection and significant performance enhancement. At 20 mA/cm2, the HyLEDs had a low operation voltage of 6.1 V, 0.8 V lower than that of OLEDs with an organic hole transport layer. With an optimized layer structure, the HyLEDs reached 104 cd/m2 brightness at 7.3 V. At this brightness level, the current efficiency was 55.2 cd/A, 57% higher than that of the OLEDs. In the IHyLEDs, facile hole injection and transport through WO3 was balanced by electron injection from the indium-tin-oxide (ITO) cathode overcoated with nanometer-thick Ca, leading to a low turn-on voltage of ∼6 V. Brightness of 8133 cd/m2 was reached at 20 mA/cm2 and the corresponding current efficiency was 40 cd/A. The hybrid devices also exhibited markedly improved stability under constant-current stressing due to the robust WO3 hole transport layer.

scholarly journals Study of Nanostructured Polymeric Composites Used for Organic Light Emitting Diodes and Organic Solar Cells

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Nguyen Nang Dinh ◽  
Do Ngoc Chung ◽  
Tran Thi Thao ◽  
David Hui
Keyword(s):  
Solar Cells ◽  
Organic Solar Cells ◽  
Light Emitting Diodes ◽  
Hole Transport ◽  
Organic Light Emitting Diodes ◽  
Transport Layer ◽  
Nanocomposite Films ◽  
Hole Transport Layer ◽  
Light Emitting ◽  
Organic Light

Polymeric nanocomposite films from PEDOT and MEH-PPV embedded with surface modified TiO2nanoparticles for the hole transport layer and emission layer were prepared, respectively, for organic emitting diodes (OLEDs). The composite of MEH-PPV+nc-TiO2was used for organic solar cells (OSCs). The characterization of these nanocomposites and devices showed that electrical (I-Vcharacteristics) and spectroscopic (photoluminescent) properties of conjugate polymers were enhanced by the incorporation of nc-TiO2in the polymers. The organic light emitting diodes made from the nanocomposite films would exhibit a larger photonic efficiency and a longer lasting life. For the organic solar cells made from MEH-PPV+nc-TiO2composite, a fill factor reached a value of about 0.34. Under illumination by light with a power density of 50 mW/cm2, the photoelectrical conversion efficiency was about 0.15% corresponding to an open circuit voltageVoc= 0.126 V and a shortcut circuit current densityJsc= 1.18 mA/cm2.

Study of nanostructured polymeric composites used for organic light emitting diodes and organic solar cells

2012 ◽  
Vol 9 (5) ◽  
pp. 399-406
Author(s):  
Do Chung ◽  
Nguyen Dinh ◽  
Tran Thao ◽  
Nguyen Nam ◽  
Tran Trung ◽  
...  
Keyword(s):  
Solar Cells ◽  
Organic Solar Cells ◽  
Light Emitting Diodes ◽  
Hole Transport ◽  
Organic Light Emitting Diodes ◽  
Transport Layer ◽  
Nanocomposite Films ◽  
Hole Transport Layer ◽  
Light Emitting ◽  
Organic Light

Polymeric nanocomposite films from PEDOT and MEH-PPV embedded with surface modified TiO2 nanoparticles were prepared, respectively for the hole transport layer (HTL) and emission layer (EL) in Organic Light Emitting Diodes (OLED). The composite of MEH-PPV + nc-TiO2 was used for Organic Solar Cells (OCS). The results from the characterization of the properties of the nanocomposites and devices showed that electrical (I-V characteristics) and spectroscopic (photoluminescent) properties of the conjugate polymers were enhanced due to the incorporation of nc-TiO2 in the polymers. The OLEDs made from the nanocomposite films would exhibit a larger photonic efficiency and a longer lasting life. For the OSC made from MEH-PPV + nc-TiO2 composite, the fill factor (FF) reached a value as high as 0.34. Under illumination of light with a power density of 50 mW/cm2, the photoelectrical conversion efficiency (PEC) was found to be of 0.15% corresponding to an open circuit voltage VOC = 1.15 V and a short-cut circuit current density JSC = 0.125 mA/cm2.

The Study of Hole Injection in OLEDs with Ultra-Thin Sol-Gel TiO2 Layer

2011 ◽  
Vol 189-193 ◽  
pp. 42-46
Author(s):  
You Wang Hu ◽  
Xiao Yan Sun ◽  
Jian Duan
Keyword(s):  
Sol Gel ◽  
Hole Transport ◽  
Organic Light Emitting Diodes ◽  
Transport Layer ◽  
Hole Injection ◽  
Hole Transport Layer ◽  
Carrier Injection ◽  
Light Emitting ◽  
Organic Light ◽  
Pre Treatment

Organic light-emitting diodes (OLEDs) with inserting an ultrathin sol–gel titanium oxide (TiO2) buffer layer between the ITO anode and hole transport layer (HTL) were fabricated. The carrier injection and the device efficiency were affected by surface morphology of TiO2, which was changed by different plasma pre-treatment of ITO. Treated by CF4 plasma, the TiO2 layer is the smoothest, and treated by H2 plasma it is like island. The TiO2 layer like island is favor of carrier injection from the anode, which was attributed to the point discharged.

Simulation and Optimization of C60-Based Organic Light-Emitting Diodes

2021 ◽  
Vol 1026 ◽  
pp. 142-146
Author(s):  
Shuo Wang
Keyword(s):  
Indium Tin Oxide ◽  
Light Emitting Diodes ◽  
Hole Transport ◽  
Organic Light Emitting Diodes ◽  
Transport Layer ◽  
Hole Transport Layer ◽  
Optical Parameters ◽  
Light Emitting ◽  
Simulation And Optimization ◽  
Organic Light

In this work we present a detailed analysis of the current-voltage variance from tris(8-hydroxyquinoline)aluminum (Alq3) based organic light emitting diodes using general-purpose photovoltaic device model (GPVDM) software as a function of: the choice of C60, the thickness of emission layer and hole-transport layer. The electrical and optical parameters of all layers were extracted from the material directory available in GPVDM. The calculations fully consider dispersion in glass substrate, indium tin oxide anode, the organic layers as well as the dispersion in the metal cathode. As expected, applied voltage was strongly dependent on the thickness of the function layer inside the devices. Finally, guidelines for designing devices with optimum turn-on voltage and thickness are presented.

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