Harvard University researchers have designed more than 1,000 blue light molecules, which when used in OLED can greatly improve the display efficiency of OLED TVs, smartphones and tablets.
OLED screens use light-emitting organic molecules that emit light when current passes through them. Unlike common liquid crystals, OLED screens do not require a backlight device. This means that OLED displays are thin and flexible and can be as simple as a piece of plastic. Each pixel on the OLED display can be turned on and off independently, greatly improving screen color contrast and energy efficiency. In high-end consumer products, OLEDs are gradually replacing LCDs. However, OLEDs' low stability and insufficient blue light materials have also caused OLEDs to become less competitive in large-size displays such as TVs.
An interdisciplinary team of Harvard researchers worked with MIT and Samsung to develop a large-scale, computer-controlled screening process, which they called the "Molecular Space Shuttle." It added R&D-stage chemical processes, machine learning, and cheminformatics to quickly identify new OLED molecules that meet or exceed industry standards.
Professor Alán Aspuru-Guzik of the Department of Chemical Biology said: "It is generally believed that the atoms of OLED are limited to a small area of molecular space. However, through the use of complex molecular builders (Molecular Builder), supplemented by state-of-the-art machine learning and the expertise of researchers, we have discovered a large part of high-efficiency blue OLED raw materials."
The biggest challenge is to produce cost-effective blue OLEDs.
Like LCD technology, OLED uses green, red and blue sub-pixels to create all the colors seen by the naked eye on the screen. But it has always been difficult to produce OLEDs that can emit blue light. To improve efficiency, OLED manufacturers create organometallic complex molecules that use conversion precious metals such as iridium to enhance the molecules with phosphorescence.
This is expensive to make and still fails to achieve a stable OLED blue light effect.
Aspuru-Guzik and his team are pursuing alternatives to these organometallic complex systems, hoping to use only organic molecules.
The research team started by building a database of more than 1.6 billion preexisting molecules and gradually narrowed the scope. A team of researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences, led by Ryan Adams, assistant professor in the Department of Information Engineering, has developed a new machine learning algorithm that can predict which molecules are likely to produce useful effects and prioritize those molecules for testing. This initiative significantly reduces the computational cost of research.
This method of screening atoms can not only be used on OLED.
Professor Aspuru-Guzil said: "This research is just a relay point to stimulate more higher-order organic atoms that can be applied in flow batteries, solar cells, organic lasers and more other fields. The future development of accelerated molecular dynamics designs is exciting."
This research was sponsored by Samsung Advanced Technology Research Institute.
ANNA