Abstract: The present invention introduces a novel design for active matrix displays, utilizing both organic light-emitting diode (OLED) and thin-film electroluminescent technologies. In a first aspect there is provided a top-emitting OLED, including an optical interference contrast-enhancing stack that is placed on the top of the driving thin-film transistor, and which extendes to the entire pixel area to cover the reflecting parts of the pixel. In a second aspect, there is provided a bottom-emitting OIED wherein an optical interference contrast-enhancing stack is placed right under the driving thin-film transistor and, separately between the organic stack and the top electrode, typically a cathode. The optical interference contrast-enhancing stack suppresses light reflection from the thin-film transistor and the upper electrode.

Abstract: An electroluminescent device having high-contrast and/or high-reliability is provided. The electroluminescent device comprises a pair of electrodes—at least one of which is transparent to electroluminescent light, and a phosphor layer which is disposed between the electrodes. The phosphor layer has a host crystal lattice, a first dopant and a second dopant. The first dopant cooperates with the host crystal lattice to cause light emission when a voltage is applied across the pair of electrodes, and the second dopant further distributes the first dopant in the host crystal lattice to increase light emission from the phosphor layer.

Abstract: The present invention provides a novel organic electroluminescent device having an optical interference member which reduces the overall reflectance from the device. The invention is particularly suited to current-driven organic displays having an anode, an electroluminescent layer and a cathode, where at least one optical interference member is placed between two of the layers and thus forms part of the electrical circuit required to excite the display. The optical interference member is chosen to have a thickness which causes at least some destructive optical interference of ambient light incident on the display. In addition, the material(s) of the optical interference member are chosen to have a work function which is compatible with the highest occupied molecular orbital, or the lowest unoccupied molecular orbital of the electroluminescent layer, depending on the location of the optical interference member in relation to the anode, cathode and electroluminescent layer.

Abstract: Bandgap engineering of thin-film electroluminescent (TFEL) devices increases their efficiency and brightness. An alternating current thin-film electroluminescent display has two stacked dielectrics, a semiconductor active layer therebetween, and metallic cladding electrodes at each side thereof. The semiconductor layer is developed by automated thermal co-evaporation so as to provide a monotonic decrease of the band gap thereof from the respective interfaces with the stacked dielectrics to the middle of the semiconductor active layer so that the dopant concentration thereof is maintained at about 0.7 %.

Abstract: The present invention provides an electroluminescent device having a dark layer for reducing at least a portion of ambient light incident on the display. In one bottom emitting device embodiment, the dark layer is placed between the emitting layer and a reflective rear cathode. The dark layer comprises a partially reflective layer, an absorptive-transmissive layer, and a reflective layer.

Abstract: We introduce an alternative concept to increase the efficiency and brightness of thin-film electroluminescent (TFEL) devices. The method utilizes bandgap engineering of the active layer of the device. First steps of our work using a ZnSxSe1−x alloy are also presented to demonstrate workability of the method. The related obstacles and future potentials of the bandgap engineering for monochrome and color TFEL devices, are discussed.

Abstract: An electroluminescent device having high-contrast and/or high-reliability is provided. The electroluminescent device comprises a pair of electrodes—at least one of which is transparent to electroluminescent light, and a phosphor layer which is disposed between the electrodes. The phosphor layer has a host crystal lattice, a first dopant and a second dopant. The first dopant cooperates with the host crystal lattice to cause light emission when a voltage is applied across the pair of electrodes, and the second dopant further distributes the first dopant in the host crystal lattice to increase light emission from the phosphor layer.