Session Index

In this study, a novel method for fabricating phosphor-free InGaN-based LEDs using cost-effective nanosphere lithography with mono-sized nanospheres is introduced. The induction of various degrees of spectral blue-shift is known to occur when nanopillars of different sizes are fabricated, a phenomenon attributed to the reduction of the Quantum Confined Stark Effect. In this work, a distribution of nanopillar clusters resulting in a broadband white emission, is realized by controlling the concentration of the mono-sized nanosphere solution. Under current operation, white emission is achieved with a color rendering index of 76.

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In this study, the rose petal surface structure on the surface of phosphor layer of the phosphor converted light-emitting diodes (pcLEDs) was fabricated to reduce the angular color variation. The two-step fabrication process was used to fabricate the rose petal surface structure on the surface of phosphor layer directly. It is found that the rose petal surface structure on the surface of phosphor layer on pcLEDs can reduce the angular color variation, and then improve the color uniformity.

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The effects of doping a small amount of chiral dopant S811 into a binary liquid crystal (LC) mixture of CB7CB and E55 have been thoroughly investigated. Due to the unique molecular structure of the LC dimer CB7CB, it influences various properties, including changes in dielectricity, flexoelectricity, and elastic constant, resulting in the emergence of distinct optical states. These modifications contribute to shorter response times in LC displays and improved optical stability in the left-handed tilted-twist state.


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In this report, we studied Inkjet Printing of Zinc Oxide(ZnO), a material normally used as the Electron Transport Layer(ETL) in Quantum-Dot Light Emitting Diode(QLED). To improve the uniformity of the deposited ZnO film through inkjet printing in pixels using a co-solvent system. so, the Flatness ratio(Fr) of Zinc Oxide Nanoparticle (ZnO NP) Ink in D was initially observed to be 0.3. the addition of the co-solvent lowered Fr to 0.01. And, the External Quantum of Efficency(EQE) of fabricated QLED increased from 1.5% to 3.2% as the uniformity of the ZnO film improved.

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We explained the mechanism of the molecules ordering by the different coating method. The emission layer (EML) of organic light-emitting diode (OLED) was fabricated by the spin coating method and bar coating method, respectively. By the bar coating method, the organic molecules within the EML are aligned. We verified the correlation between molecular ordering and device performance based on various analyzes such as complex dielectric anisotropy and molecular crystallinity. The electro-optical characteristics of the OLED device were quantitatively compared.

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The study investigates how the light source's illuminance, correlated color temperature (CCT), distance to the black-body locus (Duv), and color rendering indices (CRI) affect the user's perceptual attributes when viewing cosmetic color. The results show that a light source design with a high illuminance level, high CCT, high color rendering, and Duv=0 or -0.02 is beneficial to improving the three perceptual attributes.

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To improve electro-optical performance, we propose metal oxide nanoparticles on anode of organic light-emitting diode (OLED). When metal oxide nanoparticles are coated on the anode, the work function of the anode changes. We calculated the change of the work function of the anode, which improve the hole injection performance of OLED.

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The hyperspectral imaging technology successfully inspects the throughput spectra of the white and warm white LEDs at various positions by a home-built instrument. The results present the difference in diffuse and conversion efficiency of various phosphors in white and warm white LEDs from the data of various light throughput at the center and the side positions of the main light-delivering spot.

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A polymer-stabilized cholesteric liquid crystals (CLCs) doped with bent-shape molecules was studied. Applied with a vertical electric field, the proposed CLCs can be converted from a stable ULH state to the other stable state, addressed as a mixed state. The dopant of bent-shape molecules in CLCs affects the electro-optical properties of the mixed state and the ULH state. The mixed state is investigated by polarized optical microscope (POM), while the ULH state is measured about its rotation angle to evaluate the flexoelectric effect.

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With students’ class needs and physiological and psychological health as the core, students’ visual fatigue in blue light with different band composition under the same white light (same color temperature 4000K) and different desk illuminance (400lx and 700lx) is discussed. In this study, the blink rate is as the parameter of the objective visual fatigue. The results found the subjects in 400lx white light environment have more visual fatigue than in 700lx white light environment and they have less visual fatigue in the while light with blue pumps of 420nm.

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This study explores the difference in different pixel contact ratio using AlGaInP epitaxial material for fabrication of 80x80 μm² pixel size. Single devices are arranged in a 3x3 pixel array, and micro-LEDs are fabricated with different contact ratios (0.8, 0.6, 0.4, and 0.2) between the cathode metal (AuGe/Au) and the n-GaAs layer. Flip-chip bonding is employed for backside light emission measurements to eliminate light obstruction caused by metal deposition and enhance light extraction efficiency. Discuss the results separately for the four contact ratio, including current-voltage characteristics, light output power, external quantum efficiency, and electroluminescence spectral analysis.

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This study investigates users’ concentration under different lighting scenarios. Genetic algorithms are used to generate specific lighting spectra with different correlated color temperatures and circadian stimulus. An electroencephalogram device is used to measure the brainwaves during the psychophysical experiments. Subjective assessments are obtained via questionnaires. The signal processing of acquired brainwaves includes the time-frequency analysis using Hilbert-Huang transform, and the time-domain analysis characterized by the fractal dimension obtained from the Higuchi method.

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A psychophysical experiment is devised to explore the impact of differences in text-background brightness on visual comfort while using a head-up display in dark condition. Sixty participants are taking part in this experiment, with a balanced distribution of 20 individuals in each of the following age groups: young, middle-aged, and older participants. Each observer is tasked with evaluating a total of 190 paired comparisons. The results show that the older observers tend to prefer the lightness difference around 100, however, the young observers tend to prefer the lightness difference around 50 when reading on the head-up display.

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We present an innovative microlens array (MLA) as an optical diffuser for laser scanning smart headlights. The MLA achieves uniform energy distribution, overcoming the "hot spot" issue. By precise glass etching control, beams with FWHM divergence from 5° to 34° were fabricated. This advancement holds promise for enhancing laser scanning smart headlight performance and autonomous vehicle technology.

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We propose a digital etching technology that employs multi-step etching and
treatment to mitigate sidewall defects exposed after mesa dry etching. In this study, by twostep etching and N2 treatment, the electrical properties of the diodes show an increase of
forward current and a decrease in reverse leakage due to suppressed sidewall defects. We also
demonstrated only 1.1% decrease in output power density for a 10×10-µm2 LED as compared
with a 100×100-µm2 device without performing digital etching.

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We applied control theory to analyze the stability issues of the lighting system with degradable organic light-emitting diode (OLED) by system characteristics. Our simulation result of system parameters indicated that the close-loop control with feedback and compensation is essential to improve the system stability as OLED intrinsically degraded.

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This study examines a popular TFT-based microLED (μLED) pixel circuit using pulse width modulation (PWM) driving and explores its device variation tolerance. It highlights the importance of compensating for both threshold voltage and mobility, revealing challenges in achieving gamma 2.2 in PWM pixel circuits.

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Perovskite quantum dots (PeQDs) have the advantage of narrow FWHM, high PLQY and high absorption coefficient. However, PeQDs are easily decomposed oxygen and moisture due to their ionic bonding structure. To solve this problem, PeQDs are encapsulated with PFPE-based fluoropolymer resin. Crosslinked fluoropolymer matrix prevents decomposition of PeQDs owing to blocking oxygen and moisture. PeQD color conversion layers are fabricated on blue OLED devices. In this study, the fabricated green and red devices retained their initial PL intensity of ~72% and ~100% over 100 days, respectively.

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The AlGaInP-based red micro light-emitting diode (micro-LED) arrays in 620nm wavelength are demonstrated in our works. The micro-LED arrays with 10x10 pixels in 13x20 mesa size were fabricated which achieved enhancement with surface treatment and light improvement with surface roughness We also measured and comparing the characteristics of micro-LED arrays with and without the surface roughness in (NH4)2Sx passivation treatment.

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The LED arrays define the light-emitting area using multi-energy arsenic ion implantation, all with the same light-emitting area. As the pixel size reduces (from 50×50 μm² 1 pixel to 5×5 μm² 100 pixels), LOP and EQE decrease. Based on PL analysis, we assume that this reduction is due to light absorption by defects caused by ion implantation. Assuming a higher sidewall surface ratio for smaller pixel sizes, the defect density increases, resulting in lower LOP and EQE. Despite not achieving the elimination of sidewall effects, the micro-LED arrays still maintain excellent electrical performance and EL uniformity.

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To fabricated a linearly polarized OLED, not only the hole transport layer must be used as an alignment layer, but also the molecules of the emission layer (EML) must have a liquid crystalline phase. Since the EML material with a liquid crystalline phase is limited so the emission spectrum of linearly polarized OLED is also limited. We fabricated linearly polarized OLEDs that emit green and blue light, respectively. Using the emission spectra of two different colors, we propose a simulation algorithm in the color coordinates depending on concentration conditions.

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Tuning the local surface plasmon resonance (LSPR) peak to UVC spectral region is
important to achieve plasmonic-enhanced AlGaN-based light-emitting diodes. In this study, we
chose the height of aluminum nano-rod and the thickness of underlying SiO2 spacer as the major
tuning parameters for extinction spectrum. We observed that reducing the height of aluminum
nano-rod height to 50 nm~ 60 nm effectively brings the LSPR peak to UVC spectral region, and
the peak wavelength be fine-tuned with SiO2 spacer thickness.

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This study examines the performance of HPP drivers in terms of power and color shift at low grayscale, and further investigates the impact of PPI variation on product applications. Based on the quantified results of power and color shift, these findings serve as reference factors for early-stage circuit design.

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In order to enhance the luminous efficiency of GaN-based micro-LED and the poor heat dissipation performance of sapphire substrate, flip-chip bonding and laser lift off technology were adopted to remove the sapphire substrate, and simultaneously form GaN thin-film. The gallium atoms generated after laser lift off are etched by HCl:H2O = 1:1 at room temperature for reducing the light radiated from MQW to be absorbed. The 4 M of KOH etching at 50 ℃ for 1 min and 2 min makes the output power and EQE of the GaN-based blue micro-LED be improved.

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In recent years, organometal halide perovskite light-emitting diodes (LEDs) have attracted widespread attention due to rapid advances in device efficiency. However, rapid degradation under continuous operation is one of the major issues limiting perovskite light-emitting diode (PeLED) technology. In general, ion migration is the most important source of PeLED degradation. Therefore, under this background, this experiment uses transient ion drift to study the role of ion migration in MAPbBr3 perovskite and quasi-two-dimensional perovskite.

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Chiral nematic liquid crystal is nematic liquid crystal with chirality; thus, the molecules tend to rotate helically. The inherent helical structure of chiral nematic liquid crystal results in various optical features, such as optical activity, Bragg diffraction, and scattering, depending on the orientations of the molecules. In this work, we aim to modulate the molecular arrangements of polymer-stabilized chiral nematic liquid crystals and thus their optical features by two-photo polymerization direct laser writing (2PP-DLW). The influence of the writing parameters on the polymer-stabilized chiral nematic liquid crystals is discussed.

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The uniform lying helix (ULH) structure formed by cholesteric liquid crystals (CLCs) has a negative optical birefringence, different from that of nematic liquid crystals (NLCs) commonly used in displays.
NLCs have a positive birefringence, while negative birefringence often requires a special molecular structure, such as discotic LC molecules.
In this study, CLCs composed of different constituents were used to form the stable ULH state.
We measure the phase difference of the ULH structure and calculate the corresponding birefringence.

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Tröger’s base containing carbazole was designed and synthesized to serve as a host material for phosphorescent organic light-emitting diode (OLED) applications. Tröger's base is C2 symmetric, offering high Tg values (171–211°C) for thermal stability. Its unique V-shaped twisted structure has been used to create amorphous host materials for OLEDs with high thermal stability. From the tests, it has been determined that it can serve as a green phosphorescent host for Ir(ppy)3, achieving an EQE of 11.8% and a Von dropping to 2.6V, showcasing commendable efficiency. In the future, through component improvements, even better efficiency is expected.


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The augmented reality system primarily integrates virtual information into the sight
of an observer to achieve an augmented reality effect.Multiple augmented reality systems can
be applied to a tour bus. How to effectively allocate hardware resources for accelerating the
computation speed is a key issue when the computing power of each augmented reality system
is limited.Thus,this paper intends to accelerate the computation speed of the augmented reality
system using a distributed computing framework.In the experiment,one host device shares
image frames with the other two client devices for object detection. The computation speed
using two and three devices is approximately 1.4and1.8 times that of a single device.

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