Explore the vast range of titles available.

Many advanced technologies have been employed in high-performance active matrix displays, including liquid crystal displays, organic light-emitting diode displays, and micro-light-emitting diode displays. On the other side, there exists a strong demand for cost reduction, and it is one of the low-cost schemes for integrating the driver circuit in a panel based on thin-film transistor technologies. This paper reviews the overall concept, operation principles, and various circuit approaches in shift registers for scanning pulse generation. In addition, it deals with the implementation of additional functionalities in gate drivers to support pixel compensation, multi-line driving, in-cell capacitive touch screen, pixel sensing, and adaptive scanning region control.

Pixel circuits are key components of flat panel displays, including liquid crystal displays (LCDs), organic light-emitting diode displays (OLEDs), and micro light-emitting diode displays (micro-LEDs). Depending on the active layer material of the thin film transistor (TFT), pixel circuits are categorised into amorphous silicon (a-Si) technology, low-temperature polycrystalline silicon (LTPS) technology, metal oxide (MO) technology, and low-temperature polycrystalline silicon and oxide (LTPO) technology. In this review, we outline the fundamental display principles and four major TFT technologies, covering conventional single-gated TFTs to novel two-gated TFTs. We focus on novel pixel circuits for three glass-based display technologies with additional mention of pixel circuits for silicon-based OLED and silicon-based micro-LED.

Large-scale growth of transition metal dichalcogenides and their subsequent integration with compound semiconductors is one of the major obstacles for two-dimensional materials implementation in optoelectronics applications such as active matrix displays or optical sensors. Here we present a novel transition metal dichalcogenide-on-compound-semiconductor fabrication method that is compatible with a batch microfabrication process. We show how a thin film of molybdenum disulfide (MoS 2 ) can be directly synthesized on a gallium-nitride-based epitaxial wafer to form a thin film transistor array. Subsequently, the MoS 2 thin film transistor was monolithically integrated with micro-light-emitting-diode (micro-LED) devices to produce an active matrix micro-LED display. In addition, we demonstrate a simple approach to obtain red and green colours through the printing of quantum dots on a blue micro-LED, which allows for the scalable fabrication of full-colour micro-LED displays. This strategy represents a promising route to attain heterogeneous integration, which is essential for high-performance optoelectronic systems that can incorporate the established semiconductor technology and emerging two-dimensional materials. A two-dimensional transition metal dichalcogenide-on-compound-semiconductor fabrication method enables the realization of an active matrix micro-LED display.

Organic light-emitting transistors, three-terminal devices combining a thin-film transistor with a light-emitting diode, have generated increasing interest in organic electronics. However, increasing their efficiency while keeping the operating voltage low still remains a key challenge. Here, we demonstrate organic permeable base light-emitting transistors; these three-terminal vertical optoelectronic devices operate at driving voltages below 5.0 V; emit in the red, green and blue ranges; and reach, respectively, peak external quantum efficiencies of 19.6%, 24.6% and 11.8%, current efficiencies of 20.6 cd A –1 , 90.1 cd A –1 and 27.1 cd A –1 and maximum luminance values of 9,833 cd m –2 , 12,513 cd m –2 and 4,753 cd m –2 . Our simulations demonstrate that the nano-pore permeable base electrode located at the centre of the device, which forms a distinctive optical microcavity and regulates charge carrier injection and transport, is the key to the good performance obtained. Our work paves the way towards efficient and low-voltage organic light-emitting transistors, useful for power-efficient active matrix displays and solid-state lighting. Vertical organic light-emitting transistors are realized by using a porous base electrode in the centre of the device, which improves efficiency and reduces operating voltage by regulating charge transport and forming an optical microcavity.

This paper proposed a novel sensing circuit using a charge integrator (CI) to compensate for the thin-film transistors (TFTs) in organic light-emitting diode (OLED) displays. A higher CI initialization voltage is commonly preferred for sensing various TFT characteristics, but this may turn on OLED with a low threshold voltage. The proposed sensing circuit separates the initialization voltages for the TFT and the CI, allowing accurate TFT current sensing regardless of OLED characteristics. The suggested method calculates the threshold voltage (V TH ) and the transconductance parameter (K) of TFT using currents sensed at two gate-source voltages (V GS s) for compensation. Real-time compensation is achieved by performing sensing within vertical blanking time. We simulated compensation performance under ΔV TH and ΔK variations of ±0.5 V and ±10%, which demonstrated the current deviation decreased from a maximum of 70.20% to 1.07%. We then fabricated an 11-inch active-matrix OLED (AMOLED) panel to verify the compensation performance. The measurement results revealed that the current deviation decreased from a maximum of 38.11% to 2.55%. The compensation performance was successfully demonstrated with an 11-inch AMOLED panel. The proposed sensing circuit allows CI to be used regardless of OLED characteristics, making it suitable for a wider range of display applications.

Amorphous IGZO TFTs play a critical role in low-temperature polycrystalline oxide (LTPO) technology, enabling energy-efficient AMOLED displays and next-generation flexible electronics. However, their intrinsic instability, mainly caused by oxygen vacancies, often leads to high threshold voltage and poor device reliability, limiting further advancements in AMOLED power efficiency and long-term stability. In this work, we propose a Controlled Annealing Process (CAP) to enhance the electrical stability of IGZO TFTs. By optimizing annealing temperature and duration, we effectively suppress oxygen vacancies, as confirmed by XPS and energy band analysis. Devices annealed at 400 °C for 30 minutes exhibit minimal threshold voltage shift (<0.1 V) and improved subthreshold swing and on/off ratio. This method offers a practical route toward low-Vth and reliable IGZO TFTs for high-performance AMOLED applications.

Metal oxide optoelectronics is an emerging field that exploits the intriguing properties of the ns orbital-derived isotropic band structure as a replacement for traditional silicon-based electronics in advanced active-matrix information displays. Although the device performance of metal oxide thin film transistors (TFTs) has been substantially improved, the device reliability against external light and gate bias stress remains a critical issue. This paper provides a literature review of light-induced gate bias stress instability in metal oxide TFTs and explain the importance of photo-bias instability in the applications of metal oxide TFTs to optoelectronic device. The rationale of threshold voltage ( V th ) instability under the negative bias illumination stress (NBIS) condition is discussed in detail. The charge trapping/injection model, oxygen vacancy photoionization model, and ambient interaction model are described as plausible degradation mechanisms. Finally, the possible approaches to prevent NBIS-induced V th instability are proposed based on an understanding of the NBIS instability.

This paper proposes a novel pixel circuit and driving scheme that adopts low-temperature polycrystalline silicon and oxide thin-film transistors (LTPO TFTs) for mobile devices using active-matrix organic light-emitting diode (AMOLED) displays. The proposed pixel circuit and driving scheme provide uniform luminance and render flicker invisible at variable refresh rates (VRRs) from 1 to 120 Hz. Using the proposed pixel circuit with extended compensation time (t COMP ) improves the luminance uniformity at a high-frame rate. The proposed driving scheme applies a voltage to the driving TFTs (D-TFTs) higher than the programmed data voltage during the skip frame. This reduces the flicker caused by the hysteresis of D-TFTs during low-frame rate driving. A 6.0-inch quad high-definition (QHD) LTPO-based AMOLED display was fabricated using the new pixel circuit and driving scheme. Experimental results of the proposed pixel circuit show that the standard deviation of luminance was reduced from 0.056 to 0.008 by extending t COMP from 2 to 8 µs. The flicker level was −51 dB, so there was no visual artifact during 1 Hz driving. A flicker-free LTPO-based AMOLED display with low power consumption is possible; driving can proceed in 1-120 Hz range.

Highlights A universal and scalable process fully compatible with organic semiconductors is developed, achieving precise micropatterning and high integration density of 6.25 × 10 4 cm −2 . All-organic active-matrix organic light-emitting diode arrays with skin-like deformability were successfully fabricated. Notably, the integrated system not only exhibits stable electroluminescence, ultralight weight (~24.3 g m −2 ), and strong conformability to complex surfaces but also paves a promising path for the development of next-generation flexible and wearable displays. Organic thin-film transistors (OTFTs) are widely recognized as promising building blocks for next-generation flexible and wearable electronics. However, scalable fabrication of high-density OTFT arrays for active-matrix applications remains highly challenging, primarily due to the incompatibility of conventional photolithography with organic semiconductors. Here, we report an all-photolithographic strategy that enables the scalable fabrication of flexible OTFT arrays with both high device density and superior charge transport characteristics. By combining synergistic interfacial modulation and dual-protection photolithography strategy of organic semiconductors, we successfully fabricated transistor arrays exhibiting an average mobility above 1.0 cm 2 V −1 s −1 and on/off ratios of ~ 10 5 . This scalable method further enables an integration density of 6.25 × 10 4  cm −2 , which is one of the highest densities reported to date for full-photolithographic OTFT active-matrix arrays. Moreover, we demonstrate seamless integration of OTFT active-matrix arrays with organic light-emitting diodes (OLEDs), yielding all-organic active-matrix OLED (AMOLED) arrays. These devices exhibit stable electroluminescence, ultralight weight (~ 24.3 g m −2 ), excellent flexibility, and skin-like display functionality with reliable pixel-level addressing. This work establishes a universal and scalable route toward high-density organic electronic systems, opening new opportunities for flexible displays, electronic skin, and next-generation wearable technologies.

This study investigated novel driving scheme for low-temperature polycrystalline silicon and oxide (LTPO) active-matrix organic light-emitting diode (AMOLED) displays under variable refresh rate (VRR) driving conditions with aim of reducing the brightness instability (i.e., flicker and luminance variation) for seamless performance. The mechanisms underlying brightness fluctuations in displays were examined, focusing on frequency-dependent differences in gate-inpanel (GIP) operations. Notably, our study revealed additional factors within the GIP operation that cause LTPO flicker and VRR performance, in addition to previously identified factors of thin-film transistor hysteresis and OLED charging. Consequently, variable GIP voltage driving method that reduced these issues and enhanced display performance was proposed. The proposed method could minimize brightness fluctuations to levels imperceptible to users and facilitate performance improvement through driving options in peripheral circuits without modifying panel design and is applicable across various applications utilizing LTPO OLED technology. Its driving scheme was validated through simulation and measurement of luminance variation during frequency transition using 6.0-inch LTPO-applied AMOLED displays. The experimental results indicated a decrease in luminance difference from 14.2% to 1.5%, particularly at extremely low brightness level of 0.2 nit. The luminance distortion decreased from 7 to less than 1, which is a just noticeable color difference (JNCD).