New 3D-printable material for flat-panel displays and wearables

This new material, derived from abundant and cost-effective elements, presents an eco-friendly and cost-efficient alternative to the precious metals traditionally used, potentially making flat-panel screens and electronic gadgets more accessible and sustainable.

Peidong Yang, the lead researcher from Berkeley Lab's Materials Sciences Division and a professor at UC Berkeley, highlighted the significance of this development: “By replacing precious metals with Earth-abundant materials, our supramolecular ink technology could be a game changer for the OLED display industry. What’s even more exciting is that the technology could also extend its reach to organic printable films for the fabrication of wearable devices as well as luminescent art and sculpture.”

The appeal of OLED technology in devices like smartphones and flat-panel TVs lies in its superior lightness, thinness, energy efficiency, and picture quality compared to other technologies. This advantage stems from OLEDs' ability to emit light directly from tiny organic molecules, bypassing the need for a backlight. However, the inclusion of rare and expensive metals like iridium in OLEDs poses a challenge.

The Berkeley Lab team's innovation involves a new material described in their recent study in Science. This material, a mix of hafnium (Hf) and zirconium (Zr) powders, forms a semiconductor ‘ink’ at low temperatures. This ink undergoes a process known as supramolecular assembly, likened to building with LEGO blocks by co-first author and UC Berkeley Ph.D. candidate Cheng Zhu. Zhu developed the material during his tenure at Berkeley Lab and UC Berkeley, highlighting its capability for stable, high-purity synthesis at reduced temperatures.

Spectroscopy experiments have shown the supramolecular ink to be a highly efficient emitter of blue and green light, key for its application in OLED displays and 3D printing. Further optical experiments demonstrated its near-unity quantum efficiency, indicating its proficiency in converting absorbed light into visible light.

The researchers have also created a thin-film display prototype from the composite ink, showcasing its potential for use in programmable electronic displays. Zhu remarked on the versatility of the material, noting its suitability for 3D-printed decorative OLED lighting and even wearable devices for safety or information display.

This supramolecular ink represents another stride towards sustainable and energy-efficient semiconductor manufacturing by Peidong Yang's lab. It follows their earlier development of a ‘multielement ink’, a room-temperature processable high-entropy semiconductor. Additionally, the supramolecular ink offers a lead-free alternative within the ionic halide perovskite family, addressing environmental and health concerns associated with high-performance halide perovskites.

The research team is now exploring the electroluminescent capabilities of the supramolecular ink, aiming to understand its full potential for efficient light-emitting devices. This study, involving contributions from several researchers and supported by the Department of Energy’s Office of Science, marks a significant step forward in the development of environmentally friendly and cost-effective materials for the electronics industry.