This paper proposed a compact a-IGZO TFT-based active matrix organic light-emitting diode (AMOLED) pixel circuit driving multiple OLEDs. The pixel size was minimized using a single capacitor and field-sequential-color (FSC) driving, allowing one pixel to control two OLEDs, halving its effective size. However, these approaches constrain the threshold voltage (VTH) detection time to 1 horizontal (1H) time, and introducing subframes for FSC driving reduces 1H time compared to the conventional approach. This leads to pressing issues related to incomplete VTH sensing and the RC delay in the DATA line. Therefore, strategies to overcome these issues were also recommended. The findings revealed that the proposed circuit improves VTH detection accuracy in low gray levels by initializing the gate-source voltage of the driving TFT according to the gray level. This enhances the uniformity in low gray levels. Also, RC delay-induced nonuniformity was mitigated by extending the initialization stage to ensure the DATA line voltage stabilizes before data programming, minimizing the data storage distortion. Finally, the proposed circuit and its operation were verified through HSPICE and experimental measurements. The fabricated circuit, with a compact size of 39.3 μ m × 39.3 μ m, achieving 646 PPI, exhibited stable operation under the designed conditions.

This paper comprehensively reviews recent advances in thin-film transistor (TFT) technologies based on three major semiconductor platforms: amorphous metal oxides, two-dimensional transition metal dichalcogenides, and organic semiconductors. As modern display technologies demand higher resolution, faster switching speeds, and greater flexibility, the performance requirements for TFTs have expanded to include high carrier mobility, low power consumption, environmental stability, and compatibility with low-temperature, scalable fabrication processes. This review highlights emerging research trends in material innovation and device engineering that are propelling the development of high-performance TFTs for next-generation display applications.

Quantum-dot light-emitting diodes (QLEDs) inherently suffer from internal optical losses caused by wave-guided and surface plasmon polariton modes, which significantly limit their light outcoupling efficiency. To overcome this limitation, we developed and evaluated polymer-based light scattering layers embedded with aluminum oxide (Al2O3) nanoparticles, integrated into QLED structures externally on the substrate surface or internally beneath the cathode. External scattering layers enhanced luminous emittance by up to 78.2% by effectively redistributing emitted light toward broader viewing angles. And internal scattering layers – positioned adjacent to the bottom electrode – achieved notable improvements in luminance (32.9%) and current efficiency (up to 67.5%) without compromising device stability. Additionally, the concentration of Al2O3 nanoparticles critically influenced the scattering behavior and emission characteristics. These findings demonstrate that nanoparticle-dispersed polymer scattering layers offer a simple, scalable, and highly effective strategy, which is expected to help enhance light extraction in next-generation QLED display technologies.

Efficient charge injection and transport are fundamental challenges in colloidal quantum dots (CQD) optoelectronic devices such as photodetectors, solar cells, and displays. Unlike traditional semiconductors, charge transport in QD films is governed by hopping mechanisms, influenced by interdot coupling, ligand chemistry, and defect states. However, many aspects of these processes remain poorly understood. The interplay between charge injection, interfacial trap states, and carrier mobility introduces complex loss pathways that hinder performance. Many key unanswered questions remain, including the influence of different QD compositions, ligand environments, and orders near the interface on charge transport. Here, we discuss the challenges that should be investigated and solved in the near future. Addressing these knowledge gaps through advanced spectroscopy, transport studies, and interfacial engineering will be crucial for unlocking the full potential of CQD for transport-based optoelectronic devices, including electroluminescence displays, paving the way for high-efficiency, low-power, and long-lifetime devices.

This paper investigated the degradation mechanism of InGaZnO (IGZO) thin-film transistors (TFTs) that depend on channel length under positive bias stress (PBS). Although the further degradation of short-channel IGZO TFTs has been previously reported, it has yet to be fully understood. Using technology computer-aided design (TCAD) simulations, we found that the primary mechanism of the channel length-dependent degradation is the additional electron trapping at channel edges where electrons are diffused from the n + region. We also observed that the degradation was minimized when the n + region had a relatively low carrier concentration. Based on these findings, we demonstrated a lightly doped drain-integrated oxide TFT and repositioned the source/drain electrodes. The TCAD simulation results verified that the proposed structure could prevent PBS-induced degradation in a short channel without compromising the drain’s current performance.

ABSTRACT Full-color holographic waveguide couplers are required in advanced augmented reality (AR) near-eye display (NED) technologies due to their superior light manipulation capabilities. However, the traditional fabrication process relies on prisms to fabricate the holographic grating structures, posing significant challenges for large-scale manufacturing. The present work addresses this issue by proposing a prism-free fabrication design for full-color waveguide couplers. Our technique utilizes wavelength shifting and multiplexing of volume holographic gratings (VHGs) with three sequential exposures on a single film. The theoretical analysis, validated by optical simulations, demonstrates flexibility in selecting propagation angles that successfully transmit the correct color spectra for each color-specific grating through the waveguide. The experimental verification, which involves the fabrication of multiplexed VHGs, demonstrates the capability of reproducing true colors, thereby making waveguides based on this technology suitable for full-color AR NEDs, which could meet the current requirements of commercial companies in healthcare, gaming, and manufacturing.

This paper proposes a novel metal–oxide (MOx) thin-film transistors (TFT)-based scan driver circuit with a DC power-supplied buffer. This circuit has two parts: a ‘carry generation block (CGB)’ and an ‘output generation block (OGB).’ The CGB generates a carry pulse by the bootstrapping effect of pull-up TFT with the aid of clock signal; clock-supplied bootstrapping. Then the OGB is controlled by the carry pulse, and the output pulse is generated by the bootstrapping effect of pull-up buffer TFT with DC power supply; DC-supplied bootstrapping. In the proposed circuit, the pull-up TFT in CGB does not need to have wide dimensions because the carry signal is separated from the large capacitive load in the pixel area. Accordingly, the capacitive load of the clock signal is significantly reduced, and the dynamic power consumption associated with clock toggling decreases remarkably compared with the conventional scan driver circuit that uses the clock-supplied bootstrapping for the wide output buffer TFT. In addition, a bootstrapping inverter in OGB makes the output pulse width the same as the clock-high duration, preventing the output pulses from overlapping, which is required for most of the organic light-emitting diode (OLED) pixel circuits with in-pixel compensation.

The subpixel size of high-resolution organic light-emitting diode (OLED) microdisplays measures a few micrometers. To achieve a full-color microdisplay, the current preference is to use photolithography technology on a white OLED instead of using a fine metal mask for patterning. The application of photolithography techniques allows for the creation of microcavity structures or color filters (CFs) to enhance color purity in each emitted color. This paper focuses on investigating specialized OLED device structures for high-resolution microdisplays. The characteristics of each structure, including efficiency and color gamut, are thoroughly discussed. The structure, combining microcavity and CF, achieves the widest color gamut, while microcavity structures show higher efficiency compared to CF-only structures. Tandem structures are also considered for improved efficiency and stability.

Metal halide perovskites (MHPs) have emerged as a highly promising candidate for next-generation light-emitting materials due to their exceptional optoelectronic properties. These properties include superior color purity, high photoluminescence quantum efficiency (PLQY), and the facile tunability of bandgap through compositional and dimensional control. Particularly, polycrystalline perovskites have been introduced as the first perovskite light-emitting diodes (PeLEDs) with superior charge mobility. However, the development of efficient and stable PeLEDs, crucial for commercialization, has proven to be a significant challenge due to the low exciton binding energy (E b) and inherent defects. Nevertheless, recent achievements have demonstrated polycrystalline PeLEDs with an external quantum efficiency (EQE) surpassing 28% and a half-lifetime (T 50) exceeding 30,000 h. In this review, we present the progress of polycrystalline PeLEDs with improved efficiency (PLQY, EQE) and stability by focusing on grain size regulation, defect passivation, and dimensional control. This review offers promising strategies for realizing polycrystalline perovskite material as a light emitter, highlights limitations and provides future perspectives for advancing PeLEDs.

Efficient charge generation is essential for tandem organic light-emitting diode (OLED) devices. In this study, we introduce a p-type copper iodide (CuI) layer within the charge generation layer (CGL) that exhibits high charge generation efficiency in tandem OLED devices. Briefly, CuI is deposited as a thin layer via thermal evaporation technique. X-ray diffraction (XRD) analysis reveals the formation of γ-CuI, and the ultraviolet-visible (UV-Vis) spectral analysis demonstrates outstanding optical transparency (∼95%) of the deposited CuI films in the visible range. The current-voltage (I-V) and capacitance-voltage (C-V) analyses show that the p-type CuI layer is a vital and excellent charge generator and enhances the current density significantly. The tandem OLED device fabricated using Bphen:Liq/CuI/HAT-CN as the CGL results in a substantial 1.9-fold increase in current efficiency compared to the single-unit OLED device, approaching the theoretical two-fold increase. These findings highlight the potential of CuI as a promising p-type material for CGL design in tandem OLED devices.