Berkeley Labs unveil 2D atomic-thin semiconductor

Berkeley Labs unveil 2D atomic-thin semiconductor

Technology News |
By eeNews Europe

Because they are ionic materials, these hybrid organic-inorganic perovskites boast special properties such as photoluminescence, color-tunability, and a unique structural relaxation not found in covalent semiconductor sheets such as graphene, boron nitride, and molybdenum disulfide

"We believe this is the first example of 2D atomically thin nanostructures made from ionic materials," says Peidong Yang, a chemist with Berkeley Lab’s Materials Sciences Division and world authority on nanostructures, who first came up with the idea for this research some 20 years ago. "The results of our study open up opportunities for fundamental research on the synthesis and characterization of atomically thin 2D hybrid perovskites and introduces a new family of 2D solution-processed semiconductors for nanoscale optoelectronic devices, such as field effect transistors and photodetectors."

Yang, who also holds appointments with the University of California (UC) Berkeley and is a co-director of the Kavli Energy NanoScience Institute, is the corresponding author of a paper describing this research in the journal Science, titled "Atomically thin two-dimensional organic-inorganic hybrid perovskites."

The research was based on Yang’s proposal to synthesize free-standing 2D sheets of CH3NH3PbI3, a hybrid perovskite made from a blend of lead, bromine, nitrogen, carbon and hydrogen atoms.

The structure and composition of individual 2D crystals were characterized using a variety of techniques to find they had a slightly shifted band-edge emission that could be attributed to structural relaxation. A preliminary photoluminescence study indicates a band-edge emission at 453 nanometers, which is red-shifted slightly as compared to bulk crystals.

This suggests that color-tuning could be achieved in these 2D hybrid perovskites by changing sheet thickness as well as composition via the synthesis of related materials, according to lead author Letian Dou.

"The well-defined geometry of these square-shaped 2D crystals is the mark of high quality crystallinity, and their large size should facilitate their integration into future devices" he hopes, concluding that both vertical and lateral heterostructures can be achieved with their technique.

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