An international research team has developed a 'self-etching' technique to process soft and unstable ionic crystal lattice semiconductors, specifically 2D perovskite thin-layer single crystals, without damaging their structure, overcoming a key challenge in optoelectronic materials. Led by researchers from the University of Science and Technology of China, Purdue University, and Shanghai Tech University, the study was published on Thursday in Nature.
The study introduces a guided 'self-etching' approach that leverages internal stress accumulated during crystal growth. By using a mild ligand-isopropyl alcohol (IPA) solution system, the researchers induced controlled in-plane self-etching at specific sites in 2D perovskite single crystals. Subsequently, they precisely filled the etched cavities with 2D perovskites of varying halogen compositions. This allowed the creation of high-quality heterojunctions within a single crystal wafer, featuring lattice continuity and atomically smooth interfaces.
In semiconductor optoelectronics, heterojunctions—interfaces formed between materials of different chemical compositions at the atomic level—allow precise control over the optical properties of each cavity. By tuning the halogens in these etched regions, researchers can design pixel-like units with adjustable emission color and brightness, a crucial step toward miniaturized and efficient optoelectronic devices.
Compared to conventional methods such as strong solvent treatment or ultraviolet patterning, this new strategy is gentler and preserves the crystal lattice from damage.
"This processing method suggests that in the future, we may integrate densely arranged microscopic light-emitting pixels of different colors on an ultra-thin material. It opens up a new material platform and design pathway for high-performance luminescent and display devices," said Zhang Shuchen, a member of the research team.
This breakthrough offers an innovative pathway for optoelectronic semiconductor processing, potentially advancing next-generation display and lighting technologies.
