Scientists at Tokyo Tech have developed an OLED that produces blue light at an unprecedented low voltage of 1.47 V, signaling a potential sea change in commercial smartphone and display systems.
A new form of upconversion organic light-emitting diode (OLED), utilizing a standard blue-fluorescence emitter, has exhibited blue light emission at a remarkably low turn-on voltage of 1.47 V. This innovation by Tokyo Tech researchers bypasses the traditionally high voltage needs for blue OLEDs and paves the way for potential improvements in both commercial smartphone screens and large display panels.
Blue light plays a critical role in light-emitting technologies and is integral to smartphone screens as well as large displays. However, achieving energy-efficient blue OLEDs has been a longstanding challenge due to the high voltages required for their operation. Existing blue OLEDs usually demand around 4 V for a luminance level of 100 cd/m2, which exceeds the industrial benchmark of 3.7 V—equivalent to the voltage of lithium-ion batteries commonly found in smartphones. This has led to an urgent imperative to create novel blue OLEDs that function at reduced voltages.
In a recent collaboration, Associate Professor Seiichiro Izawa from Tokyo Institute of Technology and Osaka University, along with researchers from the University of Toyama, Shizuoka University, and the Institute for Molecular Science, unveiled a ground-breaking OLED device with an ultralow turn-on voltage of 1.47 V for blue light emission and a peak wavelength of 462 nm (2.68 eV). This research is set to be published today, September 20, in the scientific journal Nature Communications.
The materials chosen for this OLED are crucial in determining its low turn-on voltage. Specifically, the device employs NDI-HF, 1,2-ADN, and TbPe as the acceptor, donor, and fluorescent dopant, respectively. The OLED operates via an upconversion mechanism in which holes and electrons are fed into the donor and acceptor layers respectively, combining at the donor/acceptor interface to produce a charge transfer state. Dr. Izawa highlighted that intermolecular interactions at this interface are critical for charge transfer state formation and their strength directly correlates with performance.
The energy from this charge transfer state is then selectively transferred to the emitter’s low-energy first triplet excited states, eventually resulting in blue light emission through the formation of a high-energy first singlet excited state via a process known as triplet-triplet annihilation. Dr. Izawa notes, “Due to the lower energy of the charge transfer state compared to the emitter’s bandgap, the upconversion mechanism significantly lowers the voltage needed to excite the emitter, allowing the OLED to achieve a luminance of 100 cd/m2 at merely 1.97 V.”
This research effectively realizes a new OLED capable of emitting blue light at an extraordinarily low turn-on voltage by utilizing a commonly used fluorescent emitter, thus making a meaningful contribution toward fulfilling commercial requirements for blue OLEDs. The study also underscores the critical importance of optimizing the donor/acceptor interface to control excitonic processes, and offers promising prospects not only for OLEDs but also for other organic electronic devices like organic photovoltaics.
Reference: “Blue Organic Light-Emitting Diode with a Turn-on Voltage of 1.47 V,” Published on 20 September 2023 in Nature Communications.
DOI: 10.1038/s41467-023-41208-7
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Frequently Asked Questions (FAQs) about Low-Voltage Blue OLED Technology
What is the main focus of the research by Tokyo Tech scientists?
The main focus of the research is the development of a new form of upconversion organic light-emitting diode (OLED) that emits blue light at an extraordinarily low turn-on voltage of 1.47 V. This technology has the potential to revolutionize commercial smartphone screens and large display panels by significantly reducing the voltage requirements for blue OLEDs.
Who collaborated on this OLED research project?
The research was a collaborative effort involving Associate Professor Seiichiro Izawa from the Tokyo Institute of Technology and Osaka University, along with researchers from the University of Toyama, Shizuoka University, and the Institute for Molecular Science.
What is the significance of blue light in OLED technology?
Blue light is integral for a range of light-emitting devices, including smartphone screens and large display panels. It has been a challenge to develop energy-efficient blue OLEDs due to the traditionally high voltages required for their operation.
How does this new OLED differ from conventional blue OLEDs in terms of voltage requirements?
Conventional blue OLEDs usually require around 4 V for a luminance of 100 cd/m2, which is higher than the industrial target of 3.7 V. The new OLED developed by Tokyo Tech researchers operates at a much lower turn-on voltage of 1.47 V, thus making it much more energy-efficient.
What materials are used in the new OLED device?
The new OLED device uses NDI-HF as the acceptor, 1,2-ADN as the donor, and TbPe as the fluorescent dopant. These materials play a crucial role in achieving the low turn-on voltage of 1.47 V.
What is the operating mechanism of this new OLED?
The OLED operates via an upconversion mechanism, where holes and electrons are injected into the donor and acceptor layers, respectively. They recombine at the donor/acceptor interface to form a charge transfer state, which eventually leads to blue light emission at a remarkably low turn-on voltage.
What are the potential commercial applications of this technology?
The new OLED technology holds promise for widespread commercial applications, particularly in the fields of smartphone displays and large-screen display panels. It meets the pressing industry need for blue OLEDs that can operate at lower voltages, thereby becoming more energy-efficient.
When and where was this research published?
The research findings are set to be published on September 20, 2023, in the scientific journal Nature Communications.
What other organic electronic devices could benefit from this research?
Besides OLEDs, this research could have implications for other organic electronic devices like organic photovoltaics, as the study underscores the importance of optimizing the donor/acceptor interface for controlling excitonic processes.
More about Low-Voltage Blue OLED Technology
- Nature Communications Journal
- Tokyo Institute of Technology Research Highlights
- Overview of OLED Technology
- Energy-Efficient Display Technologies
- Organic Photovoltaics Research
- Lithium-Ion Batteries in Smartphones
- Upconversion Mechanisms in Organic Electronics
- Institute for Molecular Science
- University of Toyama Research
- Shizuoka University Research
- Osaka University Research
