Analysis of Recoverable Residual Image Characteristics of Flexible Organic Light-Emitting Diode Displays Using Polyimide Substrates

Hwang, Han Wook; Hong, Sa Suk; Hwang, Sang Soo; Kim, Ki Woo; Ha, Yong Min; Kim, Hyun Jae

doi:10.1109/led.2019.2914142

Cited by 26 publications

(6 citation statements)

References 17 publications

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“…To prevent moisture penetration through the PI substrate, SiO 2 and SiN x layers were deposited in a multistack using plasma-enhanced chemical vapor deposition (PECVD). Mo was patterned by photolithography as the bottom gate of an a-IGZO TFT to exclude the influence of the charge polarity of the PI substrate. , A 300-nm-thick SiO 2 layer was deposited by PECVD as a buffer layer. Next, the a-IGZO active layer (In:Ga:Zn = 1:1:1 atomic ratio) was deposited as a 30-nm-thick layer using direct current (DC) sputtering and then patterned.…”

Section: Methodsmentioning

confidence: 99%

Performance Improvement of Self-Aligned Coplanar Amorphous Indium–Gallium–Zinc Oxide Thin-Film Transistors by Boron Implantation

Kang

Lee

Kwak

et al. 2022

ACS Appl. Electron. Mater.

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The electrical properties and device stability of a self-aligned (SA) coplanar amorphous indium−gallium−zinc oxide (a-IGZO) thin-film transistor (TFT) were investigated by implanting boron (B) into the source/drain (SD) n + region. To evaluate the effect according to the depth profile of B in the a-IGZO film, various implantation energies were applied. The electrical properties were optimized when the projection range of B was in the central vertical region of the a-IGZO film. B implantation decreased the resistivity of the a-IGZO film from 3.1 × 10 2 to 2.1 × 10 −3 Ω•cm compared to an untreated a-IGZO film, while the field-effect mobility (μ fe ) improved from 2.96 to 17.22 cm 2 /(V•s). Moreover, the fabricated SA coplanar a-IGZO TFTs with a B-doped n + region exhibited excellent stability, with a threshold voltage shift (ΔV th ) of <0.2 V during a 3000 s thermal stability test performed at 200 °C and a bias stress test under a gate voltage of ±20 V. During the implantation process, B ions with high kinetic energy collide with IGZO atoms, resulting in the formation of an oxygen vacancy (V O ) and an oxygen interstitial (O i ) simultaneously. The implanted B ions and O i are bonded such that the V O sites are maintained by the B−O reaction and can contribute to an increase in the carrier concentration in a-IGZO films, thereby increasing the conductivity of the n + region.

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Section: Methodsmentioning

confidence: 99%

Performance Improvement of Self-Aligned Coplanar Amorphous Indium–Gallium–Zinc Oxide Thin-Film Transistors by Boron Implantation

Kang

Lee

Kwak

et al. 2022

ACS Appl. Electron. Mater.

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“…The measurements were performed at the center of the sample after aging AMOLED displays for 10 min at the maximum luminance to stabilize them. Considering the hysteresis characteristics of TFTs 9 , 10 , luminance and color were measured after fixing luminance at each frequency condition, and then this process was repeated for all other luminance conditions. 10 samples were measured in consideration of reproducibility and repeatability, and the average value of the measured results was shown as the experimental result.…”

Section: Methodsmentioning

confidence: 99%

Image quality enhancement in variable-refresh-rate AMOLED displays using a variable initial voltage compensation scheme

Kim

Kim³

et al. 2022

Sci Rep

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In active matrix organic light emitting diode (AMOLED) displays, when a variable refresh rate is applied and the frame rate changes, the image’s color and luminance quality in AMOLED displays deteriorates. The frequency-dependent cognitive differences were experimentally demonstrated by using 6.76″ AMOLED displays. This phenomenon is dependent on the emission time and the data programming time on the frame rate. This degradation of the image quality during the frequency switch could be prevented by applying a variable initial voltage (VINI) to the OLED anode. For a frequency change between 60 and 120 Hz, the measured just noticeable color difference (JNCD) decreased from 7.50 to less than 1.00 in luminance, and from 2.34 to 0.02 in color. As our approach can prevent image quality distortion by utilizing an existing compensation pixel structure without additional compensation steps, it will be a promising technique for improving the picture quality in AMOLED displays.

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“…According to the simulation result, the V to between the R/G/B is different, and blue and red pixel is charging quickly in contrast to green, as a result it can be explained that the reason of the color motion blur because of emitting time difference. Even though the response time (motion blur) of the AMOLED display depends on the TFT hysteresis characteristics [42][43][44], in case of ultra-low brightness, the motion blur phenomenon depends on this explanation.…”

Section: Major Factors Leading To Picture Quality Degradationmentioning

confidence: 99%

Enhancement of picture quality on ultra-low brightness by optimizing the electrical potential required for OLED charging in the AMOLED displays

Min

Kim³

et al. 2021

Journal of Information Display

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The principal causes of the poor picture quality on active matrix organic light-emitting diode (AMOLED) displays, operating under extremely low brightness and gray-scale conditions, were analyzed and verified by measuring and modelling of the electrical simulations. Through the analysis, it was found that the deteriorated picture quality was induced by a delayed saturation voltage, which means the electric potential difference between the initial voltage applied to the anode of the OLED (V init ) and the OLED saturated voltage (V sat ) for emission. This is because the deviations of pico-ampere-level currents and delayed OLED charging prior to light emission increased the saturation voltage when there were low driving currents. Thus, we optimized the voltage by increasing V init from −4.5 to −2.7 V, effectively eliminating image deterioration by reducing the OLED charging delay. Thus, the proposed approach opens up advancements of obtaining superior picture quality with ultra-low luminance, even in the dark illuminance environments. We discuss how OLED picture quality may be enhanced under low brightness, including the driving methods, design considerations, and processes involved.

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Analysis of Recoverable Residual Image Characteristics of Flexible Organic Light-Emitting Diode Displays Using Polyimide Substrates

Cited by 26 publications

References 17 publications

Performance Improvement of Self-Aligned Coplanar Amorphous Indium–Gallium–Zinc Oxide Thin-Film Transistors by Boron Implantation

Performance Improvement of Self-Aligned Coplanar Amorphous Indium–Gallium–Zinc Oxide Thin-Film Transistors by Boron Implantation

Image quality enhancement in variable-refresh-rate AMOLED displays using a variable initial voltage compensation scheme

Enhancement of picture quality on ultra-low brightness by optimizing the electrical potential required for OLED charging in the AMOLED displays

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