Excitons are quasiparticles created from the excited state of electrons and – in accordance with research being conducted EPFL – have the potential to boost the power efficiency of everyday gadgets.
It’s an entirely new way of thinking about electronics. Excitons – or quasiparticles formed when electrons take in light – stand to change the building blocks of circuits. Scientists at EPFL have been studying their extraordinary properties so as to design more energy-efficient digital systems, and have now discovered a way to control excitons better shifting in semiconductors. Their findings come in Nature Nanotechnology.
Quasiparticles are temporary phenomena ensuing from the interaction between two particles within a strong matter. Excitons are formed when an electron absorbs a photon and moves into a higher energy state, abandoning a hole in its earlier energy state (called a “valence band” in-band concept). The electron and electron-hole are bound collectively by attractive forces, and the two together form an exciton. Once the electron falls back into the hole, it emits a photon, and the exciton ceases to exist.
In 2018, a group of scientists from EPFL’s Laboratory of Nanoscale Electronics and Structures (LANES) introduced that they had developed a transistor – one of many components of circuits – that runs on excitons rather than electrons. And for the first time, they had been able to make the transistors operate at room temperature — a vital step forward for growing applications for this technology.
To make the excitons last longer, the scientists layered two different 2D materials on high of one another: tungsten diselenide (WSe2) and molybdenum diselenide (MoSe2). The resulting material had a sparkling texture that influenced how the quasiparticles had been distributed.