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    Abstract:
    The organic light-emitting transistors (OLETs) with a novel tri-layer organic semiconducting heterostructure architecture and good performance, including record high EQE, is presented. In addition, an active-matrix display based on OLETs, without driving TFTs, will be demonstrated on a plastic substrate. The potential advantages of such technologies will be discussed.
    Keywords:
    Active layer
    Matrix (chemical analysis)
    Flexible display
    Active-matrix LCDs (liquid crystal displays) addressed by a-Si (amorphous silicon) TFTs (thin-film transistors) are being developed for graphic displays such as computer terminals. Three types of TFTs, a back-channel-etched TFT, a trilayered TFT, and a self-aligned TFT, have been developed. The authors describe the dynamic characteristics of these TFTs, especially level shift in pixel voltage. First, the dependence of the level shift voltage both on drain voltage and on gate pulse delay is demonstrated. The difference of the level shift caused by the TFT structure is then clarified. Then these results are compared to those of SPICE simulation.< >
    Oxide thin-film transistor
    Spice
    Matrix (chemical analysis)
    Citations (1)
    Thin film transistors (TFTs) are the essential elements to implement active matrix organic light-emitting diode (AMOLED) display. The TFT on the AMOLED controls the emission of the OLED. Pixel circuits are being studied to improve the display quality. Poly-crystalline silicon TFT and oxide TFT have been manufactured and integrated on glass substrates for AMOLED. Various kinds of display such as foldable, rollable, wearable and stretchable displays are being studied. In stretchable displays, the device and wires manufactured on the substrate are stretched out. The resistances of wire, parasitic capacitances are affected by stretching of the substrate. In addition, when the substrate is stretched, electrical characteristic such as threshold voltage and mobility of TFT would be able to change, which results in the luminance change of the OLED. Therefore, analysis of changes in TFT is required when the substrate is stretched, and compensation circuits are required. In this study, the compensation pixel circuit is proposed for the stretchable display. To make the circuit, IGZO was used as an active layer of the TFT and deposition by RF magnetron sputter. Insulator layer was deposited for the gate insulator using atomic layer deposition (ALD) and inter layer dielectric was formed after doping of the source-drain region in the same way after doping of the source-drain region.
    AMOLED
    Oxide thin-film transistor
    Active layer
    Flexible display
    Although liquid crystal displays (LCDs) have been available for over half a century, they were always taken as niche market products because of their rather poor performance: small viewing angles, long response time, and lack of large-area panels. The situation has changed dramatically since the availability of the active matrix (AM) LCDs, specially the amorphous silicon (a-Si:H) thin film transistor (TFT) driven LCDs. The displays manufactured on TFT LCDs will be major driving force for advancement of the TFT technology in the near future. New key impact areas of TFTs will be flexible electronics, integrated circuits, sensors, detectors, light emitting diodes, etc. Industry R&D activities have been aiming at improving the cost, yield, and throughput of large-area panels. Academic research in many universities has helped in the understanding of material properties responsible for the TFT performance as well as the underlying chemistry and physics of the fabrication processes.
    Flexible display
    Citations (109)
    An all‐screen printed oxide semiconductor thin film transistor (TFT) active‐matrix backplane (AMBP) was investigated. We introduced a new pixel layout which reduces the leakage current between source and drain electrodes. As a result, the TFT‐AMBP with 33.8 ppi for an electrophoretic display was successfully fabricated by using screen printing for the first time. The display size and resolution are 750 mm × 550mm and 33.8 ppi, respectively.
    Backplane
    Oxide thin-film transistor
    Flexible display
    Leakage (economics)
    Citations (4)
    A 7-in-diagonal active-matrix color LCD with 520 × 520 pixels addressed by a-Si thin-film transistors has been developed. The display has a wide viewing angle and a contrast ratio of 4 under intense 100 000-lx illumination. The construction and performance of the panel are described in this paper.
    Contrast ratio
    Flat panel display
    Matrix (chemical analysis)
    Full color
    Viewing angle
    Citations (17)
    This paper reports an indium zinc oxide (IZO) thin film transistor (TFT) with a multi-stacked structure that showed improved performance compared to the TFT with a single active-layer structure. Devices with a multi-stacked active-layer structure were fabricated using an IZO solution process. The determination results showed that the electrical operation and environmental stability of multi-stacked IZO TFTs were improved significantly compared to those of single active-layer IZO TFTs. The roughness of the device surface was measured by atomic force microscopy. The root mean square calculation showed that the multi-stacked active-layer IZO TFT had a smoother surface. The multi-stack structured IZO TFT showed an exceptional electron mobility of 7.75 ± 0.2 cm2/V s, an on–off current ratio of 4.67 × 105 ± 0.55 × 105, and a subthreshold swing of 1.11 V/decade. In addition, a weak threshold voltage (0.35 ± 0.42 V) that is more conducive to device driving was obtained. These results highlight the great potential of multi-stack structured IZO TFTs for applications in active-matrix backplane displays.
    Active layer
    Oxide thin-film transistor
    Solution process
    Citations (5)
    A 9-in-diagonal active-matrix liquid-crystal display with 640 × 400 pixels addressed by a-Si thin-film transistors has been developed. The display has a high contrast ratio and wide viewing angle. The construction and performance of the panel are described in this paper.
    Contrast ratio
    Flat panel display
    Matrix (chemical analysis)
    Viewing angle
    Citations (5)
    A novel method is introduced using to evaluate the quality of thin-film transistor (TFT) array for driving active-matrix display (OLED). By the means of this method, the operation states of the TFT or the defects of TFT can be judged. It is a current testing method with the advantages of fast response, excellent precision, no effect to aperture and no damage to the display array.
    Matrix (chemical analysis)
    Transistor array
    Citations (6)