Climate Change and Renewable Energy News and Discussion

On January 15, it was learned from the University of Science and Technology of China (USTC) that a research team led by Professor Zhang Shuchen, in collaboration with research teams from Purdue University and ShanghaiTech University, has for the first time achieved the controllable construction of an in-plane programmable, atomically flat "mosaic" heterostructure in two-dimensional ionic soft lattice materials. This breakthrough opens up a new path for the integration and device fabrication of low-dimensional photovoltaic materials. The relevant findings were published online in the international academic journal *Nature* on January 15.

In the semiconductor field, the ability to precisely construct heterogeneous structures laterally within a material plane is crucial for exploring novel properties, developing new devices, and driving device miniaturization. However, ionic soft-lattice semiconductors, such as two-dimensional halide perovskites, have soft and unstable crystal structures. Traditional photolithography and other processing techniques often damage the material structure due to overly violent reactions, making it difficult to achieve high-quality, controllable epitaxial lateral heterogeneous integration.

To address this challenge, the research team proposed and developed a novel method for guiding the "self-etching" of internal stress within crystals. They designed a mild ligand-solvent microenvironment that can selectively activate and utilize these internal stresses to guide the single crystal to undergo controllable "self-etching" at specific locations, thereby forming a regular square-shaped hole structure. Subsequently, the team used rapid epitaxial growth technology to precisely backfill different types of semiconductor materials, ultimately constructing a high-quality "mosaic" heterojunction with continuous lattice and atomically flat interfaces within a single wafer.
“This novel processing method does not involve ‘splicing together’ different materials, but rather guides the crystal to perform precise ‘self-assembly’ within the same complete crystal,” Zhang Shuchen said. “This means that in the future, we may be able to directly ‘grow’ densely packed tiny pixels that emit different colors of light on an extremely thin material, providing a new material system and design approach for the development of high-performance light-emitting and display devices.”