scholarly journals Interlayer Engineering of Flexible and Large Area Red Organic Light Emitting Diodes Based on a N-Annulated Perylene Diimide Dimer

2019 ◽  
Author(s):  
Mohammad Rahmati ◽  
Majid Pahlevani ◽  
Gregory Welch
Keyword(s):  
Red Light ◽  
Ambient Air ◽  
Hole Transport ◽  
Transport Layer ◽  
Hole Injection ◽  
Hole Transport Layer ◽  
Large Area ◽  
Average Roughness ◽  
Light Emitting ◽  
Slot Die

<p>Flexible red OLEDs based on a quadruple layer stack in-between electrodes with 160 mm<sup>2</sup> active area were fabricated in ambient air on PET via slot-die coating. For the OLED structure PET/ITO/PEDOT:PSS/PVK/PFO:tPDI<sub>2</sub>N-EH/ZnO/Ag the ink formulations and coating parameters for each layer were systematically evaluated and optimized. The air-stable red-light emitting material tPDI<sub>2</sub>N-EH was successfully utilized as blended homogeneous film with PFO for the emitting layer. The use of an organic hole-transport layer (PVK) and inorganic electron injection layer (ZnO) significantly improved the brightness of the reference device from 4 cd/m<sup>2</sup> to 303 cd/m<sup>2</sup>. Surface analysis using AFM measurements showed that PVK interlayer reduced the surface roughness of the hole injection layer (PEDT:PSS) from 0.45 nm to 0.17 nm, which improved the ability to form uniform emitting layers on top. In addition, the ZnO interlayer improved the average roughness of the device from 1.26 nm to 0.85 nm and reduced the turn-on voltage of the device from 5.0 V to 2.8 V.</p>

scholarly journals Interlayer Engineering of Flexible and Large Area Red Organic Light Emitting Diodes Based on a N-Annulated Perylene Diimide Dimer

2019 ◽  
Author(s):  
Mohammad Rahmati ◽  
Majid Pahlevani ◽  
Gregory Welch
Keyword(s):  
Red Light ◽  
Ambient Air ◽  
Hole Transport ◽  
Transport Layer ◽  
Hole Injection ◽  
Hole Transport Layer ◽  
Large Area ◽  
Average Roughness ◽  
Light Emitting ◽  
Slot Die

<p>Flexible red OLEDs based on a quadruple layer stack in-between electrodes with 160 mm<sup>2</sup> active area were fabricated in ambient air on PET via slot-die coating. For the OLED structure PET/ITO/PEDOT:PSS/PVK/PFO:tPDI<sub>2</sub>N-EH/ZnO/Ag the ink formulations and coating parameters for each layer were systematically evaluated and optimized. The air-stable red-light emitting material tPDI<sub>2</sub>N-EH was successfully utilized as blended homogeneous film with PFO for the emitting layer. The use of an organic hole-transport layer (PVK) and inorganic electron injection layer (ZnO) significantly improved the brightness of the reference device from 4 cd/m<sup>2</sup> to 303 cd/m<sup>2</sup>. Surface analysis using AFM measurements showed that PVK interlayer reduced the surface roughness of the hole injection layer (PEDT:PSS) from 0.45 nm to 0.17 nm, which improved the ability to form uniform emitting layers on top. In addition, the ZnO interlayer improved the average roughness of the device from 1.26 nm to 0.85 nm and reduced the turn-on voltage of the device from 5.0 V to 2.8 V.</p>

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.

scholarly journals Widely applicable phosphomolybdic acid doped poly(9-vinylcarbazole) hole transport layer for perovskite light-emitting devices

RSC Advances ◽  
2019 ◽  
Vol 9 (52) ◽  
pp. 30398-30405
Author(s):  
Yanting Wu ◽  
Zewu Xiao ◽  
Lihong He ◽  
Xiaoli Yang ◽  
Yajun Lian ◽  
...  
Keyword(s):  
Phosphomolybdic Acid ◽  
Hole Transport ◽  
Transport Layer ◽  
Hole Injection ◽  
Hole Transport Layer ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Wide Range ◽  
Selection Of ◽  
Range Selection

Perovskite light-emitting devices using a PVK:PMA hole transport layer show robust performance, allowing the wide range selection of antisolvents and hole injection layers.

scholarly journals Enhanced hole injection assisted by electric dipoles for efficient perovskite light-emitting diodes

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Xiangtian Xiao ◽  
Kai Wang ◽  
Taikang Ye ◽  
Rui Cai ◽  
Zhenwei Ren ◽  
...  
Keyword(s):  
Electric Dipole ◽  
Light Emitting Diodes ◽  
Hole Transport ◽  
Transport Layer ◽  
Hole Injection ◽  
Hole Transport Layer ◽  
Light Emitting ◽  
Hole Injection Layer ◽  
Dipole Layer ◽  
Electric Dipoles

Abstract Enhanced hole injection is essential to achieve high performance in perovskite light-emitting diodes (LEDs). Here, a strategy is introduced to enhance hole injection by an electric dipole layer. Hopping theory demonstrates electric dipoles between hole injection layer and hole transport layer can enhance hole injection significantly. MoO3 is then chosen as the electric dipole layer between PEDOT:PSS (hole injection layer) and PVK (hole transport layer) to generate electric dipoles due to its deep conduction band level. Theoretical results demonstrate that strong electric fields are produced for efficient hole injection, and recombination rate is substantially increased. Capacitance-voltage analyses further prove efficient hole injection by introducing the electric dipole layer. Based on the proposed electric dipole layer structure, perovskite LEDs achieve a high current efficiency of 72.7 cd A−1, indicating that electric dipole layers are a feasible approach to enhance perovskite LEDs performance.

Performance comparison of CuPc and 2T-NATA in organic light-emitting devices

2020 ◽  
Vol 10 (9) ◽  
pp. 1542-1547
Author(s):  
Minghui Liu ◽  
Guofeng Wang ◽  
Guanran Wang
Keyword(s):  
Luminous Efficiency ◽  
Hole Transport ◽  
Experimental Results ◽  
Transport Layer ◽  
Hole Injection ◽  
Hole Transport Layer ◽  
Chemical Components ◽  
Light Emitting ◽  
Buffer Material ◽  
20 Nm

Using CuPc as the hole buffer material, the effect of 2T-NATA and CuPc as hole buffer materials in similar structure on the performance of devices is studied. For this reason, the ITO/CuPc (20 nm)/NPBX/DPVBi (20 nm) (15 nm)/Alq3: Rubrene (10, X nm)/Alq3 (40 nm)/LIF/Al (5 nm) light-emitting device is designed. Referring to the previous papers on similar structure devices, the best effect is that the thickness of doped rubrene is 20 nm. In this paper, the thickness of Alq3 doping is 10 nm, the thickness of rubrene is adjusted to 5 nm, 10 nm, 15 nm, 20 nm and 25 nm, and the buffer thickness of CuPc is selected at 20 nm according to the previous experimental results. The experimental results show that when the thickness of rubrene is 20 nm, the yellow light and blue light of the light-emitting materials tend to balance, and the device is close to the white light device. The brightness and efficiency of the device are the highest, reaching and 21050 cd/m2 5.527 cd/A respectively. Compared with 2T-NATA as the buffer material, its luminous efficiency and brightness are improved. Through the analysis of the experimental results, we find that CuPc as a hole buffer material reduces the hole carrier injection barrier, improves the hole injection ability, and enhances the recombination probability of hole and electron, improves the luminous efficiency and brightness of the device. It is concluded that 2T-NATA is more suitable than CuPc in the aspect of practical application and energy saving. The advantage of CuPc is that it can inhibit the diffusion of chemical components in ITO to the hole transport layer, which is beneficial to the improvement on device performance and life.

Effect of Pressure and MoO3 Hole Injection Layer on the Current-Voltage Characteristics of Organic Light Emitting Diodes

2015 ◽  
Vol 1132 ◽  
pp. 160-165
Author(s):  
V.C. Anye ◽  
M.G. Zebaze Kana ◽  
Jing Du ◽  
Wole Soboyejo
Keyword(s):  
Molybdenum Trioxide ◽  
Hole Transport ◽  
Optoelectronic Properties ◽  
Transport Layer ◽  
Hole Injection ◽  
Hole Transport Layer ◽  
Adhesion Properties ◽  
Light Emitting ◽  
Organic Light ◽  
First Case

We examine the fundamental operation of an Organic Light Emitting Device with emphasis laid on the Hole Transport Layer (HTL) and the optoelectronic properties of the other layers that make up the device. Investigation of the adhesion properties together with surface morphology, electrical and optical characterization of the different layers of the device was carried out. Poly (3,4-ethylenedioxythiophene):poly (styrene sulfonate) (PEDOT: PSS) was used as the conventional HTL material in the first case. This yields the reference device or system under studies. In the second case, PEDOT: PSS was replaced by an inorganic material, molybdenum trioxide (MoO 3 ). The device performance in case two (2) revealed an improvement in performance. A couple of deposition techniques were examined together with the analysis of their effect on the resultant device properties. With the aid of theoretical models, we quantified the results obtained in terms of average pull-off forces and corresponding adhesion energies. The Derjaguin-Muller-Toporov model was utilized to model the adhesion energies between interfaces of adjacent layers of the device. Results that delineate modeling of charge transport across device interfaces are shown including the effects of pressure on the device optoelectronic properties.

Highly-Efficient Solution-Processed Organic Light Emitting Diodes with Blend V2O5-PEDOT:PSS Hole-Injection/Hole-Transport Layer

MRS Advances ◽  
2019 ◽  
Vol 4 (31-32) ◽  
pp. 1779-1786 ◽  
Author(s):  
Rohit Ashok Kumar Yadav ◽  
Mangey Ram Nagar ◽  
Deepak Kumar Dubey ◽  
Sujith Sudheendran Swayamprabha ◽  
Jwo-Huei Jou
Keyword(s):  
Power Efficiency ◽  
High Efficiency ◽  
Hole Transport ◽  
Organic Light Emitting Diodes ◽  
Transport Layer ◽  
Hole Injection ◽  
Hole Transport Layer ◽  
Injection Hole ◽  
Light Emitting ◽  
Organic Light

ABSTRACTOrganic light-emitting diodes (OLEDs) have attracted huge concern because of their intrinsic characteristics and ability to reach the pinnacle in the field of high-quality flat-panel displays and energy-efficient solid-state lighting. High-efficiency is always a key crux for OLED devices being energy-saving and longer life-span. OLEDs have encountered enormous difficulties in meeting the requirements for large-sized devices due to a major limitation in vacuum thermal evaporation technology. In multilayered OLED devices, the characteristics of the charge injection/transport layer is a crucial factor for the operating-voltage, power-efficiency and stability of the device. Transition metal oxides have shown great potential owing to their wide range of possible energy level alignments, balanced charge injection, and improvement of carrier mobilities. In this study, we report a solution-processed blend V2O5-PEDOT:PSS hole-injection/hole-transport layer (HIL/HTL) for efficient orange phosphorescent OLEDs. The electroluminescent characteristics of blend V2O5-PEDOT:PSS based devices were studied with the structure ITO/V2O5-PEDOT:PSS/CBP:Ir(2-phq)3/TPBi/LiF/Al. The V2O5-PEDOT:PSS based OLEDs displayed relatively higher device performance and low roll-off than that of the counter PEDOT:PSS device in terms of a maximum luminance of 17,670 cd m-2, power efficiency of 19.4 lm W-1, external quantum efficiency of 8.7%, and more importantly, low turn-on voltage. These results demonstrate an alternative approach based on metal oxide/organic blend HIL/HTL as a substitute of PEDOT:PSS for high-efficiency solution process OLEDs.

scholarly journals Ambient-Processed, Additive-Assisted CsPbBr3 Perovskite Light-Emitting Diodes with Colloidal NiOx Nanoparticles for Efficient Hole Transporting

Coatings ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 336 ◽  
Author(s):  
Chun-Yuan Huang ◽  
Sheng-Po Chang ◽  
Arjun G. Ansay ◽  
Zi-Hao Wang ◽  
Chih-Chiang Yang
Keyword(s):  
Indium Tin Oxide ◽  
Light Emitting Diodes ◽  
Ambient Air ◽  
Peak Position ◽  
Hole Transport ◽  
Transport Layer ◽  
Hole Transport Layer ◽  
Charge Balance ◽  
Emission Layer ◽  
Light Emitting

In this study, the electrically driven perovskite light-emitting diodes (PeLEDs) were investigated by hybridizing the organic polyethylene oxide, 1,3,5-tris (N-phenylbenzimiazole-2-yl) benzene (TPBi), and bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl) iridium III (FIrpic) with CsPbBr3 in the emission layer and adopting the colloidal NiOx nanoparticle (NP) hole transport layer. The synthesized NiOx NPs, having an average size of ~5 nm, can be spin-coated to become a smooth and close-packed film on the indium–tin–oxide anode. The NiOx NP layer possesses an overall transmittance of ~80% at 520 nm, which is about the peak position of electroluminescence (EL) spectra of CsPbBr3 emission layer. The coating procedures of NiOx NP and CsPbBr3 layers were carried out in ambient air. The novel PeLED turned on at 2.4 V and emitted bright EL of 4456 cd/m2 at 7 V, indicating the remarkable nonradiative-related defect elimination by organic additive addition and significant charge balance achieved by the NiOx NP layer.

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