Hyo Eun Jeong, Integrated M.S./Ph.D. Student>
A new display technology has been developed that increases resolution while consuming minimal power. A research team led by Professor Young Min Song from the School of Electrical Engineering at KAIST, in collaboration with Professor Hyunho Jung’s team at Gwangju Institute of Science and Technology (GIST), has implemented a “monopixel” structure in which a single pixel can independently change its color to express a variety of colors while consuming almost no power to maintain them.
The “reconfigurable low-power reflective monopixel (reconfigurable Gires–Tournois resonator, hereafter r-GT)” developed by Professor Song’s team is a technology that uses electrochromic materials—substances that change color when electricity is applied—to generate color with low power consumption. Through this, the study opens a pathway toward creating clearer AR·VR displays without increasing battery burden.
Displays are continuously reducing pixel size to achieve sharper images. However, as pixels become smaller, power consumption increases and light intensity decreases. In particular, displays used in devices such as AR·VR, which are viewed at close range, must simultaneously satisfy the requirements of extremely small pixel size and low power consumption, making them difficult to realize.
The r-GT pixel developed by the research team changes color when voltage is applied, and once changed, the color is maintained for a certain period even after the voltage is removed. In other words, power is required only when changing the color, while almost no power is needed to maintain it.
The core of this technology lies in two key elements. First is the conductive polymer “polyaniline (PANI),” whose properties change when electricity is applied. This material responds even at low voltages below 1 volt (V), and its refractive index changes, resulting in a change in color. The refractive index indicates how much light bends when passing through a material, and when this value changes, the perceived color also changes.
Second, the researchers combined a resonator structure that reflects light multiple times to enhance specific colors. This structure amplifies even small changes, enabling vivid color expression with low power consumption.
As a result, a wide color variation exceeding 220° was achieved with ultra-low power consumption of 90 μW cm⁻². In simple terms, with only about 0.00009 W per 1 cm², it is possible to represent more than half of the full color wheel (360°).
Another important feature is the “monopixel” structure. Conventional displays divide a single pixel into red (R), green (G), and blue (B) subpixels to create colors. In contrast, a monopixel allows an entire pixel to independently change color and express a variety of colors. Because it does not require subpixel division, more pixels can be implemented within the same area, leading to higher resolution and reduced light loss, resulting in clearer images.
In addition, PANI has the property of maintaining its color state for a certain period even after the applied voltage is removed. This confirms the feasibility of implementing a “memory-in-pixel” display, in which power is used only when changing colors and almost no power is required to maintain them.
The research team confirmed that the technology can achieve a wide color tuning range of 220.6°, and that pixel size can be reduced to approximately 1.5 micrometers (μm). This corresponds to an ultra-high resolution of up to about 16,900 PPI, a level at which individual pixels are difficult to distinguish with the human eye.
Furthermore, even with a single-pixel structure, it was possible to reproduce about 48.1% of the standard color gamut (sRGB), and by diversifying material combinations, richer color expression of up to approximately 69.9% was demonstrated.
The team fabricated a 5×5 monopixel array to verify performance. The energy required to change color was extremely low (2.31 mJ), confirming that colors can be expressed with up to 5.8 times less power compared to conventional LEDs. In addition, as a reflective display that utilizes external light, it was also confirmed that visibility improves under brighter ambient lighting conditions.
This study demonstrates that full-color implementation is possible with ultra-low power by combining electrochemical materials with optical resonator structures. The technology is expected to be applied to various fields where energy efficiency is important, including ultra-high-resolution near-eye displays for AR·VR, wearable devices, outdoor information displays, and electronic paper. It also suggests the potential for development into sustainable and energy-efficient display technologies by minimizing power consumption while maintaining color.
Professor Young Min Song stated, “This technology was developed to enable a wide range of colors using only a very small amount of electricity. When combined with display driving methods, it can be applied not only to ultra-high-resolution displays with lower power consumption but also to various optical technologies.”
This research was co-first authored by Hyo Eun Jeong, an integrated M.S./Ph.D. student at KAIST, with Professor Young Min Song serving as the corresponding author. The results were published online on February 28 in Light: Science & Applications (Impact Factor: 23.4).
※ Paper Title : Sub-1-volt, reconfigurable Gires-Tournois resonators for full-coloured monopixel array
※ DOI : https://www.nature.com/articles/s41377-026-02228-2
This work was supported by the Ministry of Science and ICT and the National Research Foundation of Korea (NRF), the InnoCORE-GIST program, the Nano and Materials Technology Development Program, the Future Medical Innovation Technology Development Program, the Global Research Collaboration Hub Program, and the Bio-Industry Technology Development Program funded by the Ministry of Trade, Industry and Energy (MOTIE) and KEIT.
