Researchers from the Institute of Japan has developed a new white organic LED that operates at under 1.5 volts. Current white OLED technology typically requires more than 2.5 volts to operate.
caption: The infographic depicts the proposed design for a white OLED, developed using yellow and sky-blue dopants with the lowest operating voltage reported to date
image: Institute of Science Tokyo
By using triplet–triplet annihilation to generate blue light at low voltage and adding in yellow and sky-blue dopants, the research team achieved efficient white emission.
This breakthrough could contribute to reducing energy consumption in the future in displays, including television backlights and lighting devices, advancing portable electronics and sustainable technologies.
Organic light-emitting diodes (OLEDs) offer superior visual quality, but suffer from a key limitation, white OLEDs have relatively high-power consumption, that has hindered their widespread adoption in smaller, battery-operated devices.
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.
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 breakthrough in white OLED technology. Their paper, which was published in the Journal of Materials Chemistry C on July 24, 2025, reports the successful development of a white organic electroluminescent device that operates at an unprecedentedly low voltage.
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.
The researchers introduced two differently coloured 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 colours as well. The resulting light is white, since yellow and blue are complementary colours. To properly tune the ‘whiteness’ of the output, the researchers had to carefully adjust the ratio of each dopant.
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.
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 realisation of a more energy-efficient society by enabling lower-power-consuming displays and lighting devices,” notes Izawa.