Papers by Keyword: OLED

Abstract: This work investigated green fluorescence Organic Light Emitting Diode (OLED) with four hole blocking materials HBMs. Aims to enhance color performance in QD-OLED panels to produces a set of light with red, green, and blue sub-pixels. The HBM examined in this scenario consist of: (4,7-diphenyl-1,10-phenanthroline)Bphen, Tris(8-hydroxyquinoline aluminium)Alq₃, (2,2′,2″-(1, 3,5-benzinetriyl)-tris(1-phényl-1-H-benzimidazole)TPBi, (3-phényl-4(10-naphtyl)-5-phényl-1,2,4-triazole)TAZ. These holes blockings materials have different electron mobility and different hole-blocking barriers. A numerical model based on the drift-diffusion formalism was created to study electron and hole transport in OLEDs. The model includes continuity equations, conduction diffusion current, and the Poisson equation. The simulation showed the performance of each device was affected by these properties of each HBM. The width of the emission zone depends on the HBMs employed, and when the electron mobility increases the recombination zone is wide in the HBL. It was found that the device with Bphen, Alq3, TPBi, and TAZ have electrical and optical characteristics that are respectively: Langevin recombination rate (2.25 x10²⁵ cm^-3s^-1, 1.74 x10²⁵ cm^-3s^-1, 1.04x10²⁵ cm^-3s^-1,1.79x10²⁴ cm^-3s^-1), singlet exciton density (2.87x10¹⁴ cm^-3, 2.2x10¹⁴ cm^-3, 1.31x10¹⁴ cm^-3, 0.22x10¹⁴ cm^-3), luminance (4700 cd/m², 4500 cd/m², 4400 cd/m², 3200 cd/m²). Our study provides a model system to examine the role of hole blocking materials on OLED optoelectronic properties.

Abstract: The study investigated the effect of iodine-doped pentacene film as a buffer layer in an organic light-emitting diode (OLED). In this study, an ITO (indium tin oxide)-based sample is used as a reference device for comparative purposes. In OLED devices, the buffer layers were deposited using the doping of iodine vapor with the pentacene materials under proper conditions. The thermal treatment of the doped pentacene film results in increasing the conductivity of the buffer layer. Surface morphology for the bilayer anode was carried out by FESEM (Field Emission Scanning Electron Microscope) analysis. In our work, maximum luminance of 2345 cd/m² and current efficiency of 5.4 cd/A are obtained, along with more stability performance under annealing treatment in the device structure of FTO/iodine-doped pentacene (30 nm)/TPD [N, N′-Bis(3-methyl phenyl)-N, N′-diphenylbenzidine] (44 nm)/Alq3 [Tris(8-hydroxyquinoline)aluminum(III)] (52 nm)/LiF (lithium fluoride) (5 nm)/Al (aluminum) (110 nm).

Abstract: Organic light emitting diodes (OLEDs) have been known for the next generation of display technology. In this work, we synthesized four benzo[d,e]chromene derivatives (BS01-BS04) varying the position of fluorine atom for OLED application. The compounds were characterized by ¹H and ¹³C NMR, FTIR and mass spectroscopy. Their photoluminescence properties were studied which showed the thermally activated delayed fluorescence (TADF) character from intramolecular charged transfer (ICT) transition. The compounds were used as a dopant for OLEDs in the structure of ITO/NPB/BS01-BS04/Bphen/LiF/Al. The BS02 device exhibited green colour with the current efficiency at 1.28 cd/A and the power efficiency at 0.47 Im/W.

Abstract: In this paper, we reported one vinylfluorene derivative 9,9-dihexyl-vinylfluorene and its corresponding polymers. The monomer and polymers were characterized by NMR, UV-Vis, PL and Gel Permeation Chromatography (GPC). Compared with the monomer, the polymers showed blue-shift in UV-Vis spectra but red-shift in PL spedtra. This kind of side-chain polyfluorenes could be candidates of blue OLED, organic solar cells, and so on.

Abstract: This paper reviews the use of Atomic Layer Deposition (ALD) in protective coatings. Because of the growth principle ALD allows the deposition of dense conformal films on substrates of different size and shape. Recently, ALD has received increasingly interest in deposition of protective coatings. In protective coatings oxides are the most common materials and especially Al, Ti, and Ta oxides have been applied. The use of nanolaminates enables improving the protection properties. Since ALD films are pinhole-free and often thin they are used to protect against moisture, radiation, out-gassing but not often against corrosion of metals. Very good moisture barriers are obtained with thin ALD oxide layers on polymers and cardboard. This property is also very attractive in encapsulation of OLEDs. In studies of energy technology materials protection of electrodes in Li-ion batteries, fuel cells and supercapacitors by ALD has been reported and significant improvement in the stability has been achieved. Yet another area is protection of silver jewelry from tarnishing by a thin oxide layer. In traditional corrosion protection of metals ALD films have proven to be useful in tailoring of interfaces and sealing of defects in coatings made by other techniques.

Abstract: OLED (Organic light-emitting diodes) is a kind of brand-new display technology. The production involves many processes and different equipments. We studied the optimization problem of interval of preventive maintenance in OLED processes. With the help of ExtendSim software, we perform quantitative analysis and adjusted the productive process. Considering the cost of the preventive maintenance and random corrective repair, We optimized the interval of periodic maintenance with the limit of total output and obtained the best profit and lowest maintenance cost.

Abstract: A new surface-plasmon-polariton mode energy extraction method using a deielectric extraction layer (DEL) was suggested. A numerical analysis was conducted to varify the feasibility of the extraction method and to find out the optimal values of the design pararmeters. Refractive index of the DEL should be larger than that of oragnic layers of organic light-emitting diodes. In addition, the thickness of the semi-transparent cathode had an optimal range.

Abstract: Novel four-primary displays utilizing organic light-emitting devices (OLEDs) was analyzed theoretically and experimentally. Using the fitting curves of the OLEDs electroluminescent (EL) characteristics, RGBW four-primary display is clearly shown to be more energy efficient than traditional RGB three-primary display, especially as the efficiency of the OLEDs is getting higher.

Abstract: A phosphorescent iridium in the poly (fluorene) was synthesized and characterized by UV-Vis absorption and luminescence properties. The highly thermal stable was investigated by TGA. The result shows that the polymer could be a good candidate in PLED device.

Abstract: Organic light emitting diodes (OLEDs) have the potential to compete with other rivals in applications of lighting and small size displays because of low power consumption. To achieve commercial standard, however, the luminance efficiency and device lifetime of the OLEDs still need to be improved. This work characterizes the performance of OLEDs improved by Poly (3,4-ethylenedioxythiophene) poly (styrenesulfonate) (PEDOT:PSS). PEDOT:PSS films are deposited on ITO glass by spin coating at the first, and then the hole transporting layer and electron transporting layer of the OLED materials N, N '-bis (naphthalene-1-yl)-N, N '-bis (phenyl) benzidine/tris-(8-hydroxyquinoline) aluminum (NPB/Alq₃) are thermally evaporated with 1 Å/s deposition rate. The thickness effects of the PEDOT:PSS on the OLED performance are studied. The result shows that PEDOT:PSS effectively improves the luminance of the OLEDs, where 40 nm thick PEDOT:PSS increases 12% and 30 nm thick increases 31% luminance, respectively. Furthermore, the effects of the PEDOT:PSS on the mechanical properties of the OLED are also studied.