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In this paper, a high‐reliability gate driver circuit is proposed to prevent multiple outputs. The proposed circuit ensures reliability of the pull‐up thin‐film transistor (TFT) by periodically discharging the Q node voltage to the low‐level voltage (VGL) in the off stage. In addition, the output node is composed of two pull‐down TFTs that are driven alternately to ensure stability against bias stress. Thus, because the reliabilities of the pull‐up and pull‐down TFTs can be guaranteed simultaneously, the stability of the entire circuit is improved. Based on the simulation results, the rising and falling times of the output pulse are stable within 1.77 and 1.28 μs, respectively, even when the threshold voltage of the entire TFT is shifted by +10.0 V. In addition, the ripple voltage of the proposed circuit is almost eliminated and is within 0.79% of the total swing voltage. Moreover, through current is prevented in the proposed circuit because the turn‐on durations of the pull‐up and pull‐down units are completely nonoverlapping, which suggests that unnecessary power consumption can be eliminated. Therefore, based on 2,160 stages, the total power consumption of the proposed circuit is reduced by 34.7 mW from 276.3 to 241.6 mW. [ABSTRACT FROM AUTHOR]

Abstract: Large flexible organic light‐emitting diode (OLED) display provides various electronic applications such as curved, bendable, rollable, and commercial display, because of its thinness, light weight, and design freedom. In this work, the process flow and key technologies to fabricate the world's first large size 77‐inch transparent flexible OLED display are introduced. “White OLED on TFT + color filter” method is used to fabricate the aforementioned display. On both thin‐film transistor and color filter substrates, transparent polyimide (PI) was used as plastic substrate with multi‐barrier. In case of a transparent flexible display, the multi‐barrier is required for the additional consideration to overcome the decrease of transmittance due to the difference in refractive index of the conventional multi‐barrier. We developed the special multi‐barrier to increase transparency with superior water vapor transition rate characteristic. The optimized amorphous indium gallium zinc oxide thin‐film transistors were employed on the multi‐barrier, and it shows the highly uniform electrical performance and reliability on plastic substrate. Also, the typical panel failure mechanism during laser lift‐off process caused by a particle in PI is studied, and a sacrificial layer was suggested between PI and a carrier glass to reduce the panel failure. Finally, we successfully realized the world's first 77‐inch transparent flexible OLED display with ultra‐high‐definition resolution, which can be rolled up to a radius of 80 mm with a transmittance of 40%. [ABSTRACT FROM AUTHOR]

High-mobility and highly reliable self-aligned top-gate oxide thin-film transistor (TFTs) were developed using the aluminum reaction method. Al diffusion to the oxide semiconductor and homogenization of the oxygen concentration in the depth direction after annealing were confirmed by laser-assisted atom probe tomography. The high mobility of the top-gate TFT with amorphous indium tin zinc oxide channel was demonstrated to be 32 cm2/V s. A 9.9-in. diagonal qHD active-matrix organic light-emitting diode (AM-OLED) display was fabricated using a five-mask backplane process to demonstrate an applicable solution for large-sized and high-resolution AM-OLEDs. [ABSTRACT FROM AUTHOR]

We present an analysis of the parameters affecting light engines in liquid crystal display (LCD) projectors, using actual LCD projectors as examples. The significant parameters affecting light engines in LCD projectors are evaluated using the light uniformity as the determining standard. Optimization is performed on those parameters that affect the uniformity as well as the rendering effects of the projectors, by employing our own distributed genetic algorithm. The rotation angle of the collimator and its position are shown to improve the uniformity of the LCD projection, but we find that their effect on improving the brightness is not significant. Increased length of a projectors' light tube promotes better integration results. In our study, we effectively improved the performance index of an LCD projector, increasing projection uniformity by 4% (to 91.5%) and the brightness by 12% (to 7.9 lm). [ABSTRACT FROM AUTHOR]

Process development of inverted-staggered amorphous InGaZnO thin-film transistors (a-IGZO TFTs) with wet-etched electrodes was employed in this paper. Five metals (Al, Cu, Ti, Ta, and Cr) as well as various etchants were comparatively investigated, indicating H2O2 based solution etched Ta films were good candidates for the wet-etched electrodes of a-IGZO TFTs. The aforementioned findings along with other improving attempts successfully established inexpensive processing steps and conditions with which stable a-IGZO TFTs were finally fabricated. The device performance was reasonably good enough (μFE of 6.0 cm2/V·s, Vth of 2.5 V, SS of 1.8 V/decade, and Ion/Ioff of 106) to meet the requirements of applications especially for small-sized flat panel displays. [ABSTRACT FROM AUTHOR]

A flexible hybrid substrate was developed and demonstrated for roll-to-roll (R2R) manufacturing. Layer-by-layer misalignment can be well controlled within 5 btm. Top-gate amorphous InGaZnO thin-film transistor was fabricated on the flexible hybrid substrate by R2R process for the first time. A 4.3-in. segment-type reflective Electro-Phoretic Display (EPD) display was also demonstrated to show the R2R capability of flexible substrates. [ABSTRACT FROM AUTHOR]

The article presents a study which discusses the development and performance of active-matrix organic light-emitting diode (AMOLED) displays with oxide thin-film transistors (TFTs). The study investigated the effects of back-channel interface conditions on the devices. The results of the checkerboard stimuli tests revealed that the inverted OLEDs have some advantages due to their suitable driving schemes.

The article focuses on the improvement of the image quality of an organic thin-film transistors (OTFT)-driven flexible active-matrix organic light-emitting diode (AMOLED) display by enhancing the performance of OTFTs and organic light-emitting devices (OLEDs). It uses tantalum oxide powder with a high dielectric constant as a gate insulator. It shows that the organic semiconductor layer of the OTFT was successfully modeled by a polymer separator.

The article proposes a novel pixel memory using an integrated voltage-loss-compensation (VLC) circuit for ultra-low-power thin film transistor liquid crystal displays (TFT-LCDs), which can increase the number of gray-scale levels for a single subpixel using an analog voltage gray-scale approach. It integrates the new pixel with VLC circuits under a small reflective electrode. The advanced transflective TFT-LCDs can deliver high-quality multi-color images using the proposed pixel.

The article discuses the development of amorphous-oxide thin-film-transistor (TFT) arrays as TFT backplanes for large-sized active-matrix organic light-emitting-diode (AMOLED) displays. It reveals that an amorphous-indium gallium zinc oxide (IGZO) bottom-gate TFT with an etch-stop layer provided excellent electrical performance with a field-effect mobility of 21 cm2. It proposes a new pixel circuit for AMOLED displays based on amorphous-oxide semiconductor TFT.