High Brightness Research Articles

37‐1: Invited Paper: Efficient Single‐layer Blue‐emitting OLEDs

For single‐layer OLEDs to achieve efficiencies approaching those of multilayer devices, balanced charge transport is a prerequisite. We demonstrate a single‐layer blue‐emitting OLED with unity internal quantum efficiency and an external quantum efficiency of 27.7% with minor roll‐off at high brightness. These findings lay the foundations for efficient solution‐processed OLEDs.

P‐54: XAI Models for Efficient Analysis of Temperature and Power Consumption in High‐Brightness Panels and Modules

Predicting temperature and power consumption in panels and modules under high brightness has long been a daunting and time‐intensive task, often requiring over a week of simulation work. Addressing this challenge, our study introduces a novel machine learning framework, bifurcated into panel and module stages, to streamline the data acquisition process. A key innovation in our approach is the use of symbolic regression to overcome the limitations posed by the reliance on real‐world measurements for power consumption and heat generation. Employing SPICE simulations, we estimated the current density within the panel, with subsequent validation through Explainable AI (XAI) analysis. This revealed a significant correlation between current density and panel heat generation. Our research also revisits the traditionally neglected areas outside the panel's center, uncovering their impact on heat generation. The layered complexity in modules, previously a barrier to physical sample creation and measurement, was navigated using simulation. XAI insights demonstrated the crucial roles of graphite and metal layers in heat dissipation, and the drive IC as a primary heat source. This integrated approach of real and computational data in machine learning significantly reduced the analysis timeframe from a week to mere minutes, marking a breakthrough in predictive accuracy and efficiency for high‐brightness scenarios.

P‐144: High efficiency MIP with external DBR package

In this work, we design a new type of MIP(Micro LED in Package) chips which have higher LEE(Light Extraction Efficiency) by adding an external DBR(Distributed Bragg Reflector) so that the EQE (External Quantum Efficiency) of the MIP is increased. Such MIP chips provide a new choice for Mini LED display with high brightness and low power consumption.

84‐4: Transfer of Flip‐Chip Structure micro‐LED from Sapphire to Thin Film

Micro‐LED has become a hotspot in the field of displays due to its advantages such as high brightness and self‐emission, and is regarded as the next‐generation display technology. Mass transfer of micro‐LED refers to the process of transferring a large number of chips from grown substrate to another carrier, which is one of the important methods to achieve full‐color display of micro‐LED, and how to achieve high yield and high speed in mass transfer has always been a focus of attention. In this paper, mass transfer process of micro‐LEDs is studied, wherein laser lift‐off technology is employed to separate the LEDs from the sapphire substrate. Taking advantage of adhesive differences in the film, the micro‐LED array is flipped twice to complete the mass transfer process.

91‐4: Temperature Compensation Study of Micro‐LED by Machine Learning

Micro‐LED is a new display technology that offers advantages such as high brightness, high contrast, and low power consumption. However, the performance of Micro‐LED is greatly affected by temperature, leading to color shift easily. To address this issue, this paper proposes a machine learning‐based approach for achieving global compensation, which exhibits advantages including high compensation accuracy, good smoothness, and strong generalization performance. Experimental validation using both measured and simulated data demonstrates that the proposed method achieves a single‐pixel single‐color(R) brightness prediction accuracy of 1% and the brightness prediction of multi‐pixel single‐color(R) also exhibits high accuracy. Consequently, the proposed method enables global brightness compensation and color shift compensation in Micro‐LED.

Proper motion study of the 6.7 GHz methanol maser rings

Context. Methanol masers at 6.7 GHz are well-known signposts of high-mass star-forming regions. Due to their high brightness, they enable us to derive the three-dimensional gas kinematics near protostars and young stars. Aims. We aim to understand the origin of the ring-like structures outlined by methanol maser emission in a number of sources. This emission could be, a priori, spatially associated with an outflow and/or disc around a high-mass protostar. In cases of expansion or rotation, maser proper motions should be, for instance, diverging from the ring centre or perpendicular to the ring radius. Methods. Using sensitive, three-epoch observations spanning over 8 yr with the European VLBI Network, we have started the most direct investigations of maser rings using very accurate proper motion measurements with uncertainties below ~1 km s−1. Results. We present full results for the five targets of our sample, G23.207−00.377, G23.389+00.185, G28.817+00.365, G31.047+00.356, and G31.581+00.077, where proper motions show similar characteristics; maser cloudlets do not move inwards towards the centre of the rings but rather outwards. We also include the most circular source, G23.657−00.127, in the discussion as a reference. The magnitude of maser proper motions ranges from a maximum of about 13 km s−1 to 0.5 km s−1. In two of the five sources with a high number of maser spots (>100), namely G23.207−00.377 and G23.389+00.185, we show that the size of the best elliptical model, fitted to the distribution of persistent masers, increases in time in a manner similar to the case of G23.657−00.127. Moreover, we checked the separations between the pairs of spots from distinct regions, and we were able to assess that G28.817+00.365 and G31.047+00.356 can be interpreted as showing expanding motions. We analysed the profiles of single maser cloudlets and studied their variability. Contrary to single-dish studies, the interferometric data indicate variability of the emission of single-masing cloudlets. Conclusions. In five of the six targets, namely, G23.207−00.377, G23.389+00.185, G23.657-00.127, G28.817+00.365, and G31.047+00.356, expansion motions prevail. Only in the case of G31.581+00.077 can a scenario of disc-like rotation not be excluded. Complementary observations of thermal tracers as well as searching for ultra-compact H II regions in the same sources are needed. Although the overall morphology of the maser emission has remained stable, the intensities of individual maser cloudlets varied from epoch to epoch, suggesting internal instabilities.

36‐1: Invited Paper: Submicron Narrow‐Band Phosphors in Luminescent Color Filters & Next Generation MiniLED and MicroLED Displays

Both phosphors and quantum dots are currently used in liquid crystal displays (LCDs), with GE's KSF narrow red phosphor demonstrating the best possible red color point, reliability, and efficiency. Next generation miniLED and microLED based displays require excellent color quality (gamut) and high brightness which will require color conversion materials with high EQE and narrow emission peaks. Here we describe recent advancements in submicron narrow‐band phosphors which are being implemented in next‐generation miniLED displays, and being considered for enabling full‐color microLED and luminescent color filter displays of the future due to their excellent optical performance and robust nature.

92‐4: Invited Paper: MicroLED Display Technology Entering Mass Production: Opportunities and Challenges in the New Era

MicroLED display is an innovative display technology with high brightness, wide color gamut, high aperture ratio, and excellent reliability. MicroLED represents a new era in display technology, and it is rapidly entering the mass production phase. It can be used in traditional display applications and can also be applied to various innovative display technologies, such as AR glasses, transparent displays, electric vehicles, or other new use cases, expanding the application of displays into more fields. Therefore, the most critical challenge is how to rapidly reduce costs to enable the widespread adoption of MicroLED.

19‐2: Invited Paper: Ultra high brightness Color Sequential Front‐lit LCOS

Color Sequential Front‐lit LCOS (CSFLLCOS) is a compact (<0.5cc) and high brightness (110000nits/300mW) imaging solution for AR displays. However, as large FOV AR glasses i.e. >40 o become more and more popular, a higher brightness output requirement is imposed on the imager. A new LED coupling lens and waveguide plate structure have recently been proposed to promote the polarization recycling efficiency (PCE) and TpRs ratio respectively in CSFLLCOS. It is expected that the brightness will be 50% higher.

Luminescence enhancement effects of CaxSr2‒xNb2O7:Er3+,Tm3+ phosphors for temperature sensing and anti-counterfeiting applications

Er3+- and Tm3+-doped CaxSr2‒xNb2O7 (CxS2‒xN, x = 0.6, 0.8, 1.0, 1.2, 1.4) phosphors with layered perovskite structure were designed. These phosphors exhibit a dominant emission peak at 549 nm under 980 nm laser excitation, attributed to the 4S3/2→4I15/2 transition. By increasing the content of Ca2+, the crystal field regulation of rare earth ions is realized and the luminescence enhancement is induced, which is manifested by the increase of 2H11/2,4S3/2→4I15/2 emission. Furthermore, the temperature sensing sensitivities of C0.6S1.4N:Er,Tm and C0.6S1.4N:Er,Tm based on non-thermally coupled energy levels were studied. Finally, an anti-counterfeiting imprint was prepared using phosphors, which have high brightness and excellent photothermal stability. This work not only confirms that closer ionic radii substitution enables to increase the electronic density of states, improve the crystal field symmetry and enhance the luminescence, but also provides a promising phosphor system for temperature sensing and anti-counterfeiting applications, opening up new prospects in the optimization of the optical properties of phosphors.

44‐3: High Efficiency and Brightness Quantum Rods Light Emitting Diode

Despite substantial efforts, the maximum external quantum efficiency (EQE) of red, green, and blue quantum dots remains close to 25%, limited by the outcoupling efficiency of specific device optical structures. Further improvements have primarily focused on optimizing light management. In this study, we employed rod‐shaped nanocrystals instead of sphere‐like quantum dots as the light‐emitting layer. The theoretical device outcoupling efficiency significantly increased to nearly 41% due to the intrinsic horizontal dipole alignment within the quantum rod film, nearly doubling the efficiency compared to quantum dot light‐emitting diodes (QDLEDs). As a result, we achieved record‐high EQEs of 14.1% for green quantum rod light‐emitting diodes, with maximum brightness exceeding 150,000 cd/m 2 , respectively. Our research demonstrates the immense potential of QRLEDs for display and lighting applications, paving a new way for the commercialization of nanocrystal particles.

Stereo matching algorithm using deep learning and edge-preserving filter for machine vision

Machine vision research began with a single-camera system, but these systems had various limitations from having just one point-of-view of the environment and no depth information, therefore stereo cameras were invented. This paper proposes a hybrid method of a stereo matching algorithm with the goal of generating an accurate disparity map critical for applications such as 3D surface reconstruction and robot navigation to name a few. Convolutional neural network (CNN) is utilised to generate the matching cost, which is then input into cost aggregation to increase accuracy with the help of a bilateral filter (BF). Winner-take-all (WTA) is used to generate the preliminary disparity map. An edge-preserving filter (EPF) is applied to that output based on a transform that defines an isometry between curves on the 2D image manifold in 5D and the real line to eliminate these artefacts. The transform warps the input signal adaptively to allow linear 1D filtering. Due to the filter's resistance to high contrast and brightness, it is effective in refining and removing noise from the output image. Based on experimental research employing a Middlebury standard validation benchmark, this approach gives high accuracy with an average non-occluded error of 6.71% comparable to other published methods.

Refining disparity maps using deep learning and edge-aware smoothing filter

Stereo matching algorithm is crucial for applications that rely on three-dimensional (3D) surface reconstruction, producing a disparity map that contains depth information by computing the disparity values between corresponding points from a stereo image pair. In order to yield desirable results, the proposed stereo matching algorithm must possess a high degree of resilience against radiometric variation and edge inconsistencies. In this article convolutional neural network (CNN) is employed in the first stage to generate the raw matching cost, which is subsequently filtered with a bilateral filter (BF) and applied with cross-based cost aggregation (CBCA) during the cost aggregation stage to enhance precision. Winner-take-all (WTA) strategy is implemented to normalise the disparity map values. Finally, the resulting output is subjected to an edge-aware smoothing filter (EASF) to reduce the noise. Due to its resistance to high contrast and brightness, the filter is found to be effective in refining and eliminating noise from the output image. Despite discontinuities like adiron's lost cup handle or artl's shattered rods, this approach, based on experimental research utilizing a Middlebury standard validation benchmark, yields a high level of accuracy, with an average non-occluded error of 6.79%, comparable to other published methods.

P‐40: Improvement Plan for High Brightness MiniLED BLU VR Crosstalk

With the rise of the concept of "meta‐universe", VR/AR products have received more and more attention. This paper introduces the crosstalk problem of ultra‐high resolution VR products. The mechanism of the ultra‐high resolution VR crosstalk problem is discussed. Crosstalk problems, such as the reduction of high‐light backlight by membrane optimization, are studied in depth. Finally, it briefly introduces the technical challenges facing the resolution improvement of ultra‐high resolution VR.

P‐204: Simulation Study of Temperature Profile on AMOLED Panel Under High Brightness Mode

In this paper, we present a thermal simulation model designed to accurately predict the temperature distribution of AMOLED panel when operating in high brightness mode (HBM). The model incorporates panel geometric parameters, taking into account stacking configuration and material properties of actual OLED panel module. The simulation results demonstrate excellent agreement with the measured temperature distribution, with a maximum temperature difference of less than 1.5°. This thermal simulation model holds significant potential for evaluating OLED display performance and reliability risks associated with temperature increases. It can also serve as a valuable tool for guiding panel wiring design.

P‐142: Confocal Photoluminescence and Electroluminescence of Blue InGaN/GaN Nanorod Light‐emitting Diodes with Different Passivation Approaches

The sidewall passivation is essential to achieve high micro light‐emitting diode (LED) efficiency. We investigated different sidewall passivation strategies on InGaN/GaN blue nLED, including Thermal ALD and PEALD Al2O3. The characterization of temperature and laser excitation‐dependent photoluminescence (PL) and time‐resolved photoluminescence (TRPL) were observed to determine the efficiency. Sidewall passivated‐nLED device was fabricated and characterized. The device exhibits extremely high brightness, even at low operation current.

11‐4: Invited Paper: Advanced Augmented Reality Head‐Up Display Utilizing Micro LED Display Technology

This article presents an AR HUD using micro LED technology for enhanced brightness and image quality. It utilizes micro LED's high brightness to merge AR images seamlessly with external views and employs Nature 3D technology to improve the HUD's 3D depth, significantly boosting vehicle safety.

P‐208: Ultra High‐resolution patterning technology with Fine silicon mask

Side by side RGB OLEDs‐on‐Silicon backplane holds great promise for high brightness, high resolution and low cost Micro OLED displays. The main challenge of vacuum thermal evaporation (VTE) patterning technique is to get a submricon‐size shadow distance. Herein, we have explored the relation of shadow distance with mask‐substrate gap, as well as the relationship of shadow distance with evaporation angle. The achievements verify the possibility of manufacturing the ultra‐high resolution side by side RGB AMOLEDs with >4000ppi. The study of ultra‐high resolution evaporation patterning need to be expanded for the OLED microdisplays futures.

P‐160: Improving MicroLED efficiency by p‐contract optimization

Blue InGaN/GaN CPC microLED with metallic sidewall can achieve a higher efficiency based on the dipole cloud model in FDTD and electrical model in TCAD. By merely optimizing the p‐GaN contact size, the EQE is improved by 8.7%. Such method helps to achieve high brightness with a lower power consumption.

35‐1: Invited Paper: Smart Pixelated Dimmer for High Ambient Contrast AR Displays

In augmented reality (AR) headset devices, virtual image visibility and power consumption are major challenges. In this paper, we presented smart pixelated dimmer that locally enhance the ambient contrast ratio. The dimmer is integrated with image sensor and low‐power edge AI processor to control the dimming automatically. Adopting smart pixelated dimmer provides AR devices the possibility to operate in high brightness environment.