Showing papers by "Yang Yang published in 1995"

Polymer Light-Emitting Electrochemical Cells

Abstract: A device configuration for light emission from electroactive polymers is described. In these light-emitting electrochemical cells, a p-n junction diode is created in situ through simultaneous p-type and n-type electrochemical doping on opposite sides of a thin film of conjugated polymer that contains added electrolyte to provide the necessary counterions for doping. Light-emitting devices based on conjugated polymers have been fabricated that operate by the proposed electrochemical oxidation-reduction mechanism. Blue, green, and orange emission have been obtained with turn-on voltages close to the band gap of the emissive material.

Electron injection polymer for polymer light‐emitting diodes

Abstract: We report the use of an oxadiazole‐containing polymer, poly(phenylene‐1,3,4‐oxadiazole‐ phenylene‐hexafluoroisopropylidene) (PPOPH), as the electron injection layer in polymer light‐emitting diodes. By introducing a PPOPH layer between the cathode (aluminum) and the luminescent polymer (poly(2‐methoxy‐5‐(2’‐ethyl‐hexyloxy)‐1,4‐phenylene vinylene), the device performance was significantly improved; the quantum efficiency increased by a factor of 40, close to that of the same device using calcium as the cathode. By utilizing a porous polyaniline network electrode as the anode, the operating voltage was lowered by a factor of 2 with turn on at ∼5×105 V/cm.

Polymer grid triodes

Abstract: Polymer grids comprising a body of electrically conducting organic polymer (3), which body has an open and porous network morphology, and presents an expanded surface area void-defining porous network (3) are disclosed. In most applications active electronic material (2, 4) is located within at least a portion of the void spaces defined by the porous network (3). These grids are advantageously incorporated into polymer grid triodes and especially light-emitting polymer grid triodes.

Image Enhancement with Polymer Grid Triode Arrays

Abstract: An array of polymer grid triodes connected by a common grid functions as a “plastic retina,” providing local contrast gain control for image enhancement. This simple device, made from layers of conducting polymers, functions as an active resistive network that performs center-surround filtering. The polymer grid triode array with common grid is a continuous analog of the discrete approach of Mead, with a variety of fabrication advantages and significant savings in area within the unit cell of each pixel.

Crystal Structure and Polymorphism of Dimethyl-Oligothiophenes Crystallized Epitaxially on Highly Oriented PTFE Thin Films

Abstract: The crystal structure of dimethyl-oligothiophenes grown by epitaxial crystallization on highly oriented PTFE thin films has been studied by transmission electron microscopy. The dimethyl-oligothiophenes crystallize principally in a monoclinic phase with common lattice parameters a, b, and β, but with different c for different numbers of thiophene rings: a =0.598 nm, b =0.789 nm, and β =98° and c = 1.866 nm for the tetramer, c = 2.234 nm for the pentamer and c = 2.596 nm for the hexamer. The space group is C2/m. The calculated crystallographic densities are 1.36 g/cm3, 1.39 g/cm3 and 1.40g/cm3 for the tetramer, pentamer and hexamer respectively. Polymorphism is found, with coexistence of monoclinic and orthorhombic crystal structures. The dominant phase, however, is monoclinic. The relationship between the different phases is discussed.

[Anatomical relationship of the ethmoid-sphenoid areas to the optic canal and the internal carotid artery].

Abstract: The anatomical relationships and morphologic features of the optic canal and the internal carotid artery to the lateral wall of the most posterior ethmoidal cell and the sphenoid sinus in 100 half-skulls swan middle-saggitally were investigated. The results showed: (1) The whole optic canals neighboured with the most ethmoidal cell in 39 cases, with the sphenoid sinus in 43 cases and with both of them in 18 cases; (2) The bulgings of the optic canal formed on the lateral wall of the most posterior ethmoidal cells and the sphenoid sinus were demonstrated in 48 and 47 cases respectively; (3) The marks of the internal carotid artery formed on the lateral wall of the sphenoid sinus were demonstrated in 53%-77% of all cases. The height and the thickness of the bony wall of the bulgings and marks of the optic canal and the internal carotid artery were measured. From our observation it was suggested that the variations of development and composition of the sphenoid-ethmoid sinuses, the bulging or mark of the optic canal and the internal carotid artery on the lateral wall of the most posterior ethmoidal cell and the sphenoid sinus might be the anatomical factors of severe complications in endoscopic ethmoid-sphenoid surgery.