Devices are the core components that convert electrical signals into visual information. The selection and optimization of these devices depend on the support of algorithms and simulations, which, in turn, require a deep understanding of the device's working principles. The two are mutually complementary, enabling the prediction and optimization of product performance, accelerating development cycles, reducing design costs, and driving continuous innovation in display technology. At the SID Technology Forum, technical experts from Visionox engaged in an in-depth discussion on enhancing display performance.

Refining Devices to Enhance Display Performance

High-Performance pTSF Devices Based on Material and Process Optimization

In recent years, high-performance phosphorescence-assisted thermally activated delayed fluorescence sensitized fluorescence (pTSF) devices have gained significant attention. The pTSF technology substantially improves device efficiency and reduces power consumption. However, optimizing processes and materials is critical for accelerating the mass production and application of this technology.

In terms of process improvement, Visionox studied how the arrangement of evaporation sources affects the distribution of materials in the pTSF device’s luminescent layer and its performance. The results showed that the optimized arrangement significantly enhances energy transfer from the assisted phosphorescent material to the fluorescent dye, suppressing carrier capture and thus improving device efficiency. In material design, introducing inert substituents around the fluorescent dye enhances Förster energy transfer from phosphorescence to resonant fluorescent dye while suppressing Dexter energy transfer. This design also significantly reduces carrier capture by fluorescent dyes, further boosting device efficiency.

Reducing Polycrystalline Silicon Grain Boundary Protrusions and Improving Display in Flexible AMOLED LTPS Backplane

In low-temperature polycrystalline silicon film transistor devices, the height of polycrystalline silicon film grain boundaries significantly impacts performance and the display afterimage effect. To reduce the height of grain boundaries and decrease afterimage effects, Visionox optimized parameters for the amorphous silicon deposition process and implemented a two-step amorphous silicon deposition and two-step excimer laser annealing (ELA).

The optimal method achieved a 67% reduction in the height of polycrystalline silicon grain boundaries and decreased the hole defect density at the interface between the gate and the gate insulation layer. This inhibited hole capture at the interface, leading to a 23.9% improvement in mid-term afterimage and a 17.4% improvement in short-term afterimage, providing a new approach to improving the active layer formation quality and afterimage reduction in these devices.

Improving Electrical Crosstalk Between Stacked OLED Sub-pixels

Single or stacked OLED organic common communication layers (CMM) can cause electrical crosstalk between sub-pixels due to lateral charge transfer, leading to severe RGB color deviation and poor display uniformity at low brightness. To address this, Visionox designed a suitable isolation-column arrangement. Through theoretical simulation and process verification, it was found that the isolation column structure effectively suppressed electrical crosstalk, enhanced pixel color purity, and increased the display color gamut to 94.6%.

Mechanical Simulation Assisting in Enhancing Bending Yield

Research on Mechanical Simulation of the Frame under Flexible AMOLED Module

Although mechanical simulation does not directly improve display performance, such as resolution or color accuracy, it provides critical support by ensuring the structural safety, durability, thermal stability, and optimization of manufacturing processes in display devices.

As technology advances, consumers’ demand for high screen-to-body ratios makes the terminal product's frame a vital research direction. Over the past five years, the bending radius in mass production has decreased from 0.3mm to 0.15mm and is expected to reduce further to 0.1mm in the next two years. However, a smaller lower frame increases the risk of metal wires breaking in the bending area. By building a full-process simulation model, Visionox accurately calculated the maximum stress at different positions, identifying potential fracture risks. Additionally, the study of bending trajectory calculations and simulations addressed over-tension/over-pressure issues during the bending process, improving bending yield and providing a theoretical basis for enhancing bending design and reducing the bending radius.

Further, research on the impact of buffer value on metal wires, lower pressure distance, bending radius, and pressure-sensitive adhesive highlighted the buffer value’s importance. Buffer design can address stress concentration issues, regulate lower pressure distance, and influence the choice of pressure-sensitive adhesives.

Algorithm Innovations Supporting Implementation

A JPEG-LS Near-Lossless Image Compression Algorithm Easy to Implement in Hardware

JPEG-LS is a context-based lossless/near-lossless image compression algorithm that is simple to implement, occupies minimal resources, and offers a high compression rate. It is widely used for compressing continuous-tone still images. However, JPEG-LS’s pixel-by-pixel prediction and real-time context updates can cause delays and high resource usage, hindering IP-based algorithm implementation.

To address the Demura compensation data compression needs, Visionox modified the JPEG-LS algorithm’s pixel prediction approach and postponed context updates. The optimized algorithm (NJPEG-LS) reduced Linebuffer resource usage by 8/9, achieved clock frequencies exceeding 140MHz, and kept the comprehensive compression rate loss within 4.5%, meeting the Demura compensation data compression and decompression requirements. Additionally, analyzing the distribution of the k values in the compression process revealed a regular pattern, leading to the development of an adaptive k value scheme (KNJPEG-LS) that further simplified the hardware design.

Optimization of Moire Pattern on Screen Antenna Based on Ultra-Fast and Accurate Simulation Algorithm

The Moire effect, caused by the interaction of two or more periodic structures, is often unwelcome in the display industry due to its negative impact on display quality. For example, in on-screen antenna technology, the interaction between display pixel periods and the period of the antenna’s metal grid can lead to noticeable Moire patterns and reduced display quality.

Visionox proposed an ultra-fast and accurate simulation algorithm that can simulate Moire patterns under various conditions, including any pixel arrangement, sub-pixel shape and size, optical layers, metal grid line width, line spacing, and crossing angles. Compared to traditional methods combining ray tracing and Fourier transform contrast sensitivity filtering, this algorithm reduces simulation time to one-thousandth of traditional levels and can run on standard laptop memory without requiring high-end memory setups.