Finding New Semi-Conductor Materials That Emit Light is Essential for Developing A Wide Range of Electronic Devices. But artificial making that that emit light structures tailored to our specific needs is an attractive proposal. However, light emission in a semiconductor only occurs when certain conditions are put.
Researchers from the University of Geneva (Unige), Switzerland, in Collaboration with the University of Manchester, Have Discovered An Entire Class of Two-Dimensal Materials that Are the Thickness of One or A Few Atoms. When combined tonther, these atomically think Crystals are capable of forming structures that emit custhisable light in the desired color.
This Research, Published in the Journal Nature Materials (“Design of Van der Waals interfaces for Broad-Specrum optoelectronics”), marks an important step toowards the future industrialization of Two-Dimensal Materials.
Semiconductor Materials Capable of Emitting Light are used in sectors as various as telecommunications, Light Emitting Devices (LEDs) and Medical Diagnostics. Light Emission Occurs when an Electron Jumps Inside the Semiconductor from a Higher Energy Level to a Lower Level. It is the difference in Energy that Determines the Color of the Emitted Light.
For Light to be Produced, the Velocity of the Electron Before and After the Jump Must Be Exactly the Same, On condition that depends on the specific semiconducting Material Considered. Only some semiconductors can be used for light emission: for example, silicon-used to make our computers-cannot be employed for manufacturing leds.
“We Asked Ourselves Whower Two-Dimensal Materials Could Be used to make that Emit Light with the Desired Color”, Explains Alberto Morpurgo, A Professor in the Department of Quantum Matter Physics, at the Unige Faculty of Science.
Two-dimensional materials are perfect crystals that, like graphene, are one or a few atoms thick. Thanks to Recent Technical Advances, Different Two-Dimensal Materials can be stacked on top of each other to form artificial structures that behave like semiconductors. The Advantage of These “Artificial Semi-Conductors” is that the Energy Levels can be controlled by selecting the Chemical Composition and Thickness of the Materials that make up the structure.
“Artificial semiconductors of this kind were made for the First Time Only Two or Three Years Ago”, Explains Nicolas Ubrig, A Researcher in the Team Led by Professor Morpurgo. “When the Two-Dimensal Materials Have Exactly the Same Structure and Their Crystalls Are Perfectly Aligned, this Type of Artificial Semi-Conductor Can Emit Light. But it’s very rare.” These conditions are so strict that they leave little freedom to control the light emotted.
Custom light
“our objective was to manage to combine different two-dimensional materials to emit light While being free from all constraints”, continues professor morpurgo.
The Physicists Thought that, if they could find a class of Materials where the Velocity of the Electrons Before and after the Change in Energy Level was zero, it will be an ideal scenario Which WOULD ALWAYS MEET the Conditions for Light Emission, Look of the Crystal Lattices and their relative orientation.
A Large Number of Known Two-Dimensal Semiconductors have a Zero-Electron Velocity in the receiving Energy Levels. Thanks to this Diversity of Compounds, Many different Materials can be combined, and each combination is a new artificial semiconductor Emitting Light of A specific color.
“Once we had the idea, it was easy to find the materials to use it”, Adds Professor Vladimir Fal'ko from the University of Manchester.
MATERIALS THAT WEERE USED IN THE RESEACHE INCLUDED VARIOUS METAL DICHALCOGENIDES Transition (Such As Mos2, MOSE2 and WS2) and INSE. Other possible Materials have been identified and will be used for widening the ranges of the colors of the light emited by these new artificial semiconductors.
Tailor-Made Light for Mass Industrialization
“The Great Advantage of These 2d Materials, Thanks to the Fact that are no more preconditions for the Emission of Light, is that their provide new strategies for manipulating the light as we see, with the energy and colour that we were Ubrig.
This means it is possible to currency future applications on an industrial level, since the emited light is robust and there is no long any need to make the alignment of atoms.
Source: University of Geneva