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A full-color 14-inch active matrix organic light emitting diode (AMOLED) TV, which does not suffer from the well-known pixel non-uniformity of luminance using a simple pixel circuit design consisting of 3 transistors and 1 capacitor, has been developed using amorphous hafnium-indium-zinc oxide (a-HIZO) thin-film transistors (TFTs) as an active-matrix backplane. The n-channel a-HIZO TFTs exhibit a field-effect mobility of 10 cm2/V-s, threshold voltage of 0.38V, on/off ratio of >108, and subthreshold gate swing of 0.21 V/decade. Notably, the long- and short-range standard deviations for the threshold voltage were less than 0.1V and 0.02V, respectively.

We have developed the stereo-corresponding algorithm using edge information. The conventional stereo-corresponding algorithm, SAD (Sum of Absolute Difference), has a good quality in case of texture region, but it has a false matching in the non-texture region. In order to reduce the false matching in the non-texture region, the new cost function, which is defined as SED (Sum of Edge Difference) based on the global optimization, is added to the cost function of SAD. We evaluate our algorithm and benchmark Middlebury database. The experimental results show that our proposed algorithm successfully produces piecewise smooth disparity maps while reducing the false matching in the non-texture region. Moreover, our algorithm is faster in getting the best quality than SAD.

An on-glass integrated scan driver is proposed for oxide thin film transistors TFTs with negative threshold voltage. A coupling capacitor and a TFT for setting the initial voltage to the gate of a TFT were added to minimize the off-state current. Simulated and measured results indicate that the proposed scan driver shows no ripple and fast rise time/fall time of scan outputs. Circuit operation was verified with a 14-inch AMOLED panel.

Amorphous oxide thin film transistor (TFT) arrays have been developed as TFT backplanes for large size active-matrix organic light emitting diode (AMOLED) displays. An amorphous IGZO (Indium Gallium Zinc Oxide) bottom gate TFT with an etch-stop layer (ESL) delivered excellent electrical performance with field- effect mobility of 21 cm2/V-s, an on/off ratio of >108, and subthreshold slope (SS) of 0.29V/dec. A full color 19-inch AMOLED display has been developed using the amorphous IGZO TFT backplane.

The world largest flexible full color 6.5-inch active matrix organic light emitting diode (AMOLED) display with top emission mode on plastic film is demonstrated. The active matrix backplanes were fabricated using metal oxide thin film transistors (TFTs). The n-channel metal oxide TFTs on plastic film exhibited field-effect mobility of 17.8 cm2/Vs, threshold voltage of 0.4 V, on/off ratio of 1.1× 108, and subthreshold slope of 0.34 V/dec. These TFT performance characteristics made it possible to integrate scan driver circuit, demux switching and compensation circuit on the panel. Bending tests were performed with TFT backplane samples to determine critical curvature radius to which the panel can be bent without TFT performance degradation. The results were compared with the calculations that took into account thicknesses and mechanical constants of flexible substrate and of thin-film layers in AMOLED device.

We developed a 2 inch low temperature poly-Si active-matrix organic light-emitting diode (AMOLED) with an embedded p-i-n photodiode. The pixels for both OLED and photodiode are designed using poly-Si TFT and poly-Si p-i-n. The lateral p-i-n photodiode exhibited the photo response of ∼40 dB under 100 lux. We have demonstrated the display and sensors successfully on glass. This technology can be used for AMOLED integrated with touch sensor and brightness control sensor.

In this work, we review the current technological challenges for large-Size AMOLED displays with an emphasis on the backplane technology. Then, it will be discussed how the new technology of oxide TFTs combines the advantages of LTPS and a-Si TFTs to make an optimal solution for large-Size backplanes. In particular, we reveal the technological challenges in oxide TFTs by comparing the device characteristics of conventional excimer laser annealing (ELA) LTPS and amorphous indium-gallium-zinc-oxide (a-IGZO) TFTs. Finally, we demonstrate a 12.1″ WXGA AMOLED prototype display fabricated by an a-IGZO TFT backplane.

The full color 12.1-inch WXGA active-matrix organic light emitting diode (AMOLED) display was, for the first time, demonstrated using indium-gallium-zinc oxide (IGZO) thin-film transistors (TFTs) as an active-matrix back plane. It was found that the fabricated AMOLED display did not suffer from the well-known pixel non-uniformity of luminance, even though the simple structure consisting of 2 transistors and 1 capacitor was adopted as a unit pixel circuit, which was attributed to the amorphous nature of IGZO semiconductor. The n-channel a-IGZO TFTs exhibited the field-effect mobility of 8.2 cm2/Vs, threshold voltage of 1.1 V, on/off ratio of > 108, and subthreshold gate swing of 0.58 V/decade. The AMOLED display with a-IGZO TFT array would be promising for large size applications such as note PC and HDTV because a-IGZO semiconductor can be deposited on large glass substrate (> Gen. 7) using conventional sputtering system.

We have developed a 4.0 inch pentacene organic thin-film transistors (OTFTs) based active matrix organic light-emitting diode (AMOLED) display. To achieve bright and uniform displays, we have investigated several process issues unique to OTFT-based OLEDs. A bottom contact structure was used to fabricate the pentacene TFT backplane. Fine metal masking (FMM), laser ablation technique (LAT), and polyvinyl alcohol based patterning method were used to isolate the pentacene active layer. The low processing temperature (maximum 150°C) may allow the use of polymeric substrates and lower cost processing. Uniform TFT performance is achieved with reasonably good mobility and on/off ratio. The initial OLED display performance is also presented.

The world first flexible full color 5.6-inch active matrix organic light emitting diode (AMOLED) display with top emission mode on stainless steel foil is demonstrated. The active matrix back planes were fabricated using low temperature poly-Si (LTPS). The p-channel poly-Si TFTs on the stainless steel foil exhibited the field-effect mobility of 71.2 cm2/Vs, threshold voltage of −2.7 V, off current of 6.7× 1013 A/um, and subthreshold slope of 0.63 V/dec. These TFT performances made it possible to integrate scan driver circuit on the panel. A low-cost planarization techniqe of stainless steel foil was developed to replace the expensive chemical mechanical planarization (CMP) method, which was the most critical barrier against mass production. The full color flexible AMOLED display on the stainless steel foil will be promising for mobile applications because of its thin, light, rugged, and design-free properties.

A high-resolution 5.7″ VGA mono cholesteric reflective liquid crystal display was demonstrated using a STN driver. We have reduced the driving voltage of Ch-LCD by optimizing panel conditions and adding low molecular materials. The optimized driving voltage was enough to drive the display, necessary for using a commercial STN driver.