A research team led by Lawrence Berkeley National Laboratory (Berkeley Lab) has developed “supramolecular ink,” a brand new technology to be used in OLED (organic light-emitting diode) displays or other electronic devices. Product of inexpensive, Earth-abundant elements as a substitute of costly scarce metals, supramolecular ink could enable cheaper and environmentally sustainable flat-panel screens and electronic devices.
“By replacing precious metals with Earth-abundant materials, our supramolecular ink technology might be a game changer for the OLED display industry,” said principal investigator Peidong Yang, a school senior scientist in Berkeley Lab’s Materials Sciences Division and professor of chemistry and materials science and engineering at UC Berkeley. “What’s much more exciting is that the technology could also extend its reach to organic printable movies for the fabrication of wearable devices in addition to luminescent art and sculpture,” he added.
If you could have a comparatively recent smartphone or flat panel TV, there’s a superb probability it features an OLED screen. OLEDs are rapidly expanding within the display market because they’re lighter, thinner, use less energy, and have higher picture quality than other flat-panel technologies. That is because OLEDs contain tiny organic molecules that emit light directly, eliminating the necessity for the additional backlight layer that’s present in a liquid crystal display (LCD). Nonetheless, OLEDs can include rare, expensive metals like iridium.
But with the brand new material — which the Berkeley Lab team recently described in a brand new study published within the journal Science — electronics display manufacturers could potentially adopt a less expensive fabrication process that also requires far less energy than conventional methods.
The brand new material consists of powders containing hafnium (Hf) and zirconium (Zr) that will be mixed in solution at low temperatures — from room temperature as much as around 176 degrees Fahrenheit (80 degrees Celsius) — to form a semiconductor “ink.”
Tiny molecular “constructing block” structures inside the ink self-assemble in solution — a process that the researchers call supramolecular assembly. “Our approach will be in comparison with constructing with LEGO blocks,” said Cheng Zhu, the co-first writer on the paper and a Ph.D. candidate in materials science and engineering at UC Berkeley. These supramolecular structures enable the fabric to realize stable and high-purity synthesis at low temperatures, explained Zhu. He developed the fabric while working as a research affiliate in Berkeley Lab’s Materials Sciences Division and graduate student researcher within the Peidong Yang group at Berkeley Lab and UC Berkeley.
Spectroscopy experiments at UC Berkeley revealed that the supramolecular ink composites are highly efficient emitters of blue and green light — two signifiers of the fabric’s potential application as an energy-efficient OLED emitter in electronic displays and 3D printing.
Subsequent optical experiments revealed that the blue- and green-emitting supramolecular ink compounds exhibit what scientists call near-unity quantum efficiency. “This demonstrates their exceptional ability to convert nearly all absorbed light into visible light through the emission process,” Zhu explained.
To show the fabric’s color tunability and luminescence as an OLED emitter, the researchers fabricated a thin-film display prototype from the composite ink. In an exciting result, they found that the fabric is suitable for programmable electronic displays.
“The alphabet movie serves as a compelling example that illustrates the appliance of emissive thin movies like supramolecular ink within the creation of fast-switching displays,” said Zhu.
Additional experiments at UC Berkeley showed that the supramolecular ink can also be compatible with 3D printing technologies reminiscent of for the design of decorative OLED lighting.
Zhu added that manufacturers could also use the supramolecular ink to fabricate wearable devices or high-tech clothing that illuminates for safety in low-light conditions, or wearable devices that display information through the supramolecular light-emitting structures.
The supramolecular ink is one other demonstration from the Peidong Yang lab of recent sustainable materials that might enable cost-effective and energy-efficient semiconductor manufacturing. Last yr, Yang and his team reported a brand new “multielement ink” — the primary “high-entropy” semiconductor that will be processed at low temperature or room temperature.
With their demonstrated stability and shelf life, the supramolecular ink compounds could also assist in the industrial advancement of ionic halide perovskites, a thin-film solar material that the display industry has been eyeing for many years. With their low-temperature synthesis in solution, ionic halide perovskites could potentially enable cheaper manufacturing processes for the manufacturing of displays. But high-performance halide perovskites contain the element lead, which is concerning for the environment and public health. In contrast, the brand new supramolecular ink — which belongs to the ionic halide perovskite family — offers a lead-free formulation without compromising performance.
Now that they’ve successfully demonstrated the supramolecular ink’s potential in OLED thin movies and 3D-printable electronics, the researchers at the moment are exploring the fabric’s electroluminescent potential. “This involves a focused and specialized investigation into how well our materials can emit light using electrical excitation,” Zhu said. “This step is crucial to understanding our material’s full potential for creating efficient light-emitting devices.”
Other authors on the study include Jianbo Jin (co-first writer), Zhen Wang, Zhenpeng Xu, Maria C. Folgueras, Yuxin Jiang, Can B. Uzundal, Han K.D. Le, Feng Wang, and Xiaoyu (Rayne) Zheng.
This work was supported by the Department of Energy’s Office of Science.
