Papers by Keyword: Hole Transport

Abstract: Two novel copolymers combining the electron-transporting group (Alq3), hole-transporting group (carbazole and phenothiazine) and chromophore had been obtained. The copolymers were characterized by 1H NMR, IR and UV-vis absorption spectrum, and exhibited good solubility in a wide range of organic solvents such as toluene, THF, chloroform, DMF and DMSO. GPC shows moderate molecular masses of the copolymers around 15000 and a narrower weight distribution (PDI≈1.4). The DSC and TGA measurements indicated that the resulting copolymers have excellent thermal stability and higher glass transition temperatures than the commonly used light-emitting conjugated polymers. The PL properties of the copolymers were investigated in solution and in the solid state. Only the Alq3 emission (520 nm) was observed at high concentration (10 g/L) or in solid state. However, with the decrease in concentration of the copolymer solution, the characteristic emission of carbazole appears. This means the energy transfer taken place in higher concentration is more efficient than in lower concentration solution.

Abstract: Five novel triarylamines based on the bulky dehydroabietic acid unit have been synthesised, and their potential as hole transport layers tested. This bulky group facilitates film preparation and stability without significantly affecting the chemical or materials properties. Three of these systems present excellent stability, and show considerable potential for device applications.

Abstract: Asymmetric rolling, in which the circumferential velocities of the upper and lower rolls are different, can give rise to intense plastic shear strains and in turn shear deformation textures through the sheet thickness. The ideal shear deformation texture of fcc metals can be approximated by the <111> // ND and {001}<110> orientations, among which the former improves the deep drawability. The ideal shear deformation texture for bcc metals can be approximated by the Goss {110}<001> and {112}<111> orientations, among which the former improves the magnetic permeability along the <100> directions and is the prime orientation in grain oriented silicon steels. The intense shear strains can result in the grain refinement and hence improve echanical properties. Steel sheets, especially ferritic stainless steel sheets, and luminum alloy sheets may exhibit an undesirable surface roughening known as ridging or roping, when elongated along RD and TD, respectively. The ridging or roping is caused by differently oriented colonies, which are resulted from the <100> oriented columnar structure in ingots or billets, especially for ferritic stainless steels, that is not easily destroyed by the conventional rolling. The breakdown of columnar structure and the grain refinement can be achieved by asymmetric rolling, resulting in a decrease in the ridging problem.