Papers by Keyword: Organic Light-Emitting Devices (OLEDs)

Abstract: The doped and non-doped white Organic light-emitting devices (OLEDs) were fabricated, using strong yellow emitting and hole-transporting ability of TPAHQZn. When the white OLED is a double-doped structure, greatly enhanced the efficiency of the device. The double-doped white device were fabricated as follows: ITO/2T-NATA (17 nm)/ CBP: 30% TPAHQZn: 8% Ir(ppy)3 (25 nm)/ NPBX (15 nm)/BCP(8nm)/TPBi: 10% Ir(ppy)3 (15nm)/Alq3 (20 nm)/LiF (1.3 nm)/Al. The double-doped white OLEDs were obtained with Commission International de L’Eclairage coordinates of (0.29,0.28) at 17 V, the maximum current efficiency increaed four times that double-doped white device of 4.12cd/A(8V) than non-doped of 1.03 cd/A (10V) .

Abstract: Thin layers of the OLED related polyphenylene-vinylene (PPV) deposited by a precursor on micro-fabricated Si cantilevers were studied by applying the vibrating-reed technique during repeated temperature cycling between 100 and 520 K. By means of the Langmuir-Blodgett method for film production, the dependence of damping and elastic modulus on well defined values of film thickness (16 to 69 nm) was determined. Simultaneous measurements of these quantities showed four damping peaks during heating around 130 K (called γ), 250 K (β), 350 K (β’), and 400 K (called C). Three of them (γ, β’, C) disappeared after heating to the highest temperature (520 K) indicating their presence in the precursor only. The activation parameters of the relaxation peaks (γ, β, β’) were estimated and assigned to specific atomic movements in the molecule. Peak C occurs during the conversion process of precursor to polymer. Earlier results are essentially substantiated, indicating only slight differences to those for layers produced previously by spin coating. The observed thickness dependence of damping for the γ and β peaks suggests a weaker contribution of molecules in the surface region than of those in the bulk, while the β’ peak is supposed to result from molecules in the interface region between layer and substrate.

Abstract: We have fabricated an organic light-emitting devices with high efficiency and brightness utilizing thick layer of a starburst amine compound 4,4’, 4’’-tris{N,-(3-methylphenyl)-Nphenylamin} triphenylamine (m-MTDATA) as hole injection buffer layer. The brightness and the current efficiency were comparatively improved compared with those of the device without the buffer layer. The device with 10nm m-MTDATA act as buffer layer has max brightness was 18590cd/m2 at 17 V, and the highest luminous efficiency was achieved 4.30cd/A, at 7V, which is nearly three times than that of the device without it.

Abstract: The synthesis and characterization of a series of square planar Pt(II) complexes, which are luminescent at room temperature, are reported. The complexes have the general structure of (C^N)Pt(O^O), where HC^N is 3-phenylpyridazine (ppdz), 3-(4’-biphenyl)pyridazine (4’phppdz), 3-(2’-naphthyl)pyridazine (2’napdz), or 3-(1’-naphthyl)pyridazine (1’napdz), and HO^O is acetylacetone (Hacac). The reaction of K2PtCl4 with HC^N forms the chloro-bridged dimer, (C^N)Pt( µ-Cl)2Pt(C^N), which are cleaved with an ancillary ligand to give the corresponding monomeric (C^N)Pt(O^O) complexes. The emission bands of these complexes are governed by the structure of the cyclometalating ligands, with emission band (lem) ranging from 516 to 645 nm. The two emission bands at (515 and 550 nm) of (ppdz)Pt(acac) complex have 7 and 6 ms of life time which imply those bands are due to phosphorescence decay. The conjugating ring on the pyridazine makes the emission more red shifted which is expected based on molecular orbital calculation. In addition to the alteration of cyclometalating ligands, ancillary ligands also change. These results can be compared with the corresponding Ir(III) complexes.

Abstract: Two types of the organic light-emitting devices (OLEDs) with different emission structures were prepared using Alq3 (aluminum tris 8-hydroxyquinoline) host material and quinacridone (QD) dopant at the emission layer. One is the OLED device with emission layer consisting of Alq3 host material doped with QD dopant ("codoped OLED"). The another one has a seperated QD dopant film in the Alq3 emission layer ("undoped OLED"). The maximum brightness of the codoped and undoped OLEDs were 3207 cd/m2 and 1570 cd/m2, respectively. The wavelength of the maximum emission peak in the undoped sample was 527 nm and shifted slightly toward longer wavelength with the value of 540 nm for the codoped OLED sample. The maximum luminous efficiency of the undoped OLED was about 1.4 lm/W and increased to 7.0 lm/W for the codoped sample.