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Two different external compensation methods for high‐resolution active matrix organic light‐emitting diode (AMOLED) displays are presented and compared. Both compensation methods are implemented using a small pixel circuit, namely, a 3T2C and a 2T1C pixel circuit, allowing high‐resolution displays. Due to the simple driving schemes, these methods allow fast driving, even for large displays. The characterization results show a significant improvement in current variation by implementing either of these methods. The VT compensation method using a 3T2C pixel circuit is able to reduce the current variation down to 0.56%, whereas the VT‐ and β‐factor compensation method using a 2T1C pixel circuit demonstrates a further reduction in current variations down to 0.079%. This method also clearly shows significant improvement in optical variation between neighboring pixels. [ABSTRACT FROM AUTHOR]

We present dual‐gate (DG) dual‐layer (a‐ITZO and a‐IGZO) amorphous oxide TFTs integrated on polyimide (PI) foil. The fabricated TFTs show an apparent dual‐gate field‐effect mobility (µFE) of 45.0 cm2/ (V.s), sub‐threshold slope (SS−1) of 0.40 V/decade and ION/IOFF ratio of >108. The DG dual‐layer TFT based ring‐oscillators exhibit faster oscillation frequencies (fosc) compared to DG a‐IGZO TFT based ring‐oscillators. These TFTs are paving the way to faster scan drivers and higher resolution displays. It is also verified that with DG dual‐layer TFTs, the current variation can be reduced when applying an off‐panel compensation method to the asymmetric channel. [ABSTRACT FROM AUTHOR]

A novel external VT compensation method, using a simple driving scheme, is presented, enabling high resolution, yet uniform displays, regardless of the size. The uniformity can be maintained for initial VT nonuniformities as well as VT shifts occurring during operation, like bias stress. The characterized display area shows a significant reduction in current variation, transforming ~23% variation without compensation into 0.56% variation after calibration. [ABSTRACT FROM AUTHOR]

We present a qHD (960x540 with 3 sub-pixels) top-emitting AMOLED display with 340ppi resolution using a self-aligned (SA) IGZO TFT backplane on polyimide-foil with humidity barrier. The back plane process flow is based on a 7 layer photolithography process with a CD=4um. We implement a 2T1C pixel engine and use commercial source driver IC made for LTPS. By using IGZO TFT and leveraging the extremely low off-current, we can switch-off the power to the source and gate driver while maintaining the image un-changed for several minutes. We demonstrate that, depending on the image content, low-refresh operation yields reduction in power consumption of up to 50% compared to normal (continuous) operation. We show that with further increase in resolution, the power saving through state retention will be even more significant. [ABSTRACT FROM AUTHOR]

We present a qHD (960 × 540 with three sub-pixels) top-emitting active-matrix organic light-emitting diode display with a 340-ppi resolution using a self-aligned IGZO thin-film transistor backplane on polyimide foil with a humidity barrier. The back plane process flow is based on a seven-layer photolithography process with a CD = 4 μm. We implement a 2T1C pixel engine and use a commercial source driver IC made for low-temperature polycrystalline silicon. By using an IGZO thin-film transistor and leveraging the extremely low off current, we can switch off the power to the source and gate driver while maintaining the image unchanged for several minutes. We demonstrate that, depending on the image content, low-refresh operation yields reduction in power consumption of up to 50% compared with normal (continuous) operation. We show that with the further increase in resolution, the power saving through state retention will be even more significant. [ABSTRACT FROM AUTHOR]

In this work we present the impact of buffer layers deposited by various techniques such as plasma enhanced chemical deposition (PECVD), physical vapor deposition (PVD) and atomic layer deposition (ALD) techniques on self-aligned (SA) top gate amorphous-Indium-Gallium-Zinc-Oxide (a-IGZO) TFT characteristics. Finally an optimized layer was integrated in TFT backplane on polyimide (PI) foil and a QQVGA AMOLED display is demonstrated. [ABSTRACT FROM AUTHOR]

We present a QVGA (320x240 with 3 sub-pixel) top-emitting AMOLED display with 250ppi resolution using a self-aligned (SA) IGZO TFT backplane on polyimide-foil with full barrier. The back plane process flow is based on a 7 layer photolithography process. The aperture ratio of the top-emitting OLEDs is approx. 80%. An integrated gate driver is shown that can be driven at operation speed equivalent to a 4k2k display at 100Hz. [ABSTRACT FROM AUTHOR]

An integrated scan-line driver, driving half a QQVGA flexible AMOLED display using amorphous-IGZO backplane technology on foil, has been designed and measured. A pulse-width modulation technique has been implemented, enabling to drive the OLEDs with a duty cycle up to almost 100%. The digital driving method also results in a 40% static power reduction of the display. Dynamic logic and bootstrapping techniques enabled the use of clock frequencies up to 300kHz in unipolar amorphous-IGZO technologies on foil. [ABSTRACT FROM PUBLISHER]

We present a QQVGA (160times120 with 3 sub-pixel) top-emitting AMOLED display with 85ppi resolution using a self-aligned (SA) IGZO TFT backplane on polyimide-foil. The back plane process flow is based on a 5 layer photolithography process. The aperture ratio of the top-emitting OLEDs is approx. 25%. For operation at 6 V supply voltage (VDD), the brightness of the display exceeds 150cd/m2. On the same substrate a 160 stage gate-driver was measured at FHD rate. [ABSTRACT FROM AUTHOR]