| Jul 31, 2025 |
Researchers develop ultra-low-voltage white OLED for energy-efficient displays
Researchers have created a white OLED that runs on under 1.5 volts, offering a major advance in power efficiency for portable and wearable displays.
(Nanowerk News) Organic light-emitting diodes (OLEDs) have revolutionized display technologies, bringing vibrant colors and sleek designs to everything from televisions and laptops to immersive virtual reality devices. Although OLEDs offer unparalleled visual quality, they still suffer from a key limitation—white OLEDs have relatively high-power consumption—that has hindered their widespread adoption in smaller, battery-operated devices.
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This power-hungry nature stems from the high voltage needed to produce white light. Current white OLED technology typically requires more than 2.5 volts to operate, which is the voltage required to produce the blue light from which the white light is partially derived. Despite extensive research into improving the efficiency and color quality of white OLEDs, lowering their operating voltage has remained a significant challenge.
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In a recent study, a research team led by Associate Professor Seiichiro Izawa from the Materials and Structures Laboratory at Institute of Science Tokyo (Science Tokyo), Japan, has achieved a remarkable breakthrough in white OLED technology. Their paper, which was published in the Journal of Materials Chemistry C ("White organic light-emitting diodes with extremely low turn-on voltage at 1.5 V"), reports the successful development of a white organic electroluminescent device that operates at an unprecedentedly low voltage.
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| This work will help realize lower-power displays and lighting devices with higher energy efficiency. (Image: Institute of Science Tokyo) (click on image to enlarge)
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The team built upon their previous endeavors in creating low-voltage blue OLEDs using an upconversion process based on triplet–triplet annihilation (TTA). Simply put, their strategy involves using a low voltage to drive the movement of negative and positive charges within a layered organic semiconductor device. When these charges meet and recombine, they produce excited electronic states known as triplet states. These states can ‘destroy’ each other through TTA to give rise to a higher-energy singlet state, which produces blue light as it decays.
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The researchers introduced two differently colored dopants into the emissive layer of the semiconductor device to achieve the desired white light: a sky-blue dopant (a perylene-based dopant, Tbpe) and a yellow dopant (rubrene). These dopants, energized by the high-energy singlet states in the host material, emit light of their respective colors as well. The resulting light is white, since yellow and blue are complementary colors. To properly tune the ‘whiteness’ of the output, the researchers had to carefully adjust the ratio of each dopant.
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The newly developed white OLED boasts a turn-on voltage of less than 1.5 volts. This exceptionally low voltage requirement means the device can be directly operated by a single 1.5-volt dry battery. “To the best of our knowledge, this is the lowest operating voltage reported to date for white OLEDs,” highlights Izawa.
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By enabling lower operating voltages in white OLEDs, this study could lead to new display designs in portable electronics, including wearable devices for entertainment, sports, and health applications. “Our achievement could contribute to the realization of a more energy-efficient society by enabling lower-power-consuming displays and lighting devices,” notes Izawa.
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As the research team continues to refine this technology and address a few remaining challenges, such as efficiency and color stability, this work brings us closer to a future where even high-quality displays consume minimal energy.
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