Room-Temperature Chiral Light-Emitting Diode Based on Strained Monolayer Semiconductors

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Information Science

Background:

• Chiral light sources with electrically switchable optical helicity are crucial for optical quantum information processing.
• Monolayer semiconductors offer chiral luminescence via valley polarization, but practical devices are limited to low temperatures.
• Existing valley-polarized light-emitting diodes (LEDs) typically operate below 80 K.

Purpose of the Study:

• To realize a room-temperature chiral LED.
• To investigate the role of strain in achieving robust valley-polarized electroluminescence.
• To enable electrically tunable optical helicity for practical applications.

Main Methods:

• Fabrication of chiral LEDs using strained transition metal dichalcogenide monolayers.
• Spatially resolved polarization spectroscopy to analyze valley-polarized electroluminescence.
• Design and implementation of strained conditions on flexible substrates.

Main Results:

• A room-temperature chiral LED was successfully realized.
• Strain effects were identified as critical for robust valley-polarized electroluminescence.
• Broken threefold rotational symmetry in strained monolayers induced inequivalent valley drifts, enabling electric-field-driven spin recombination.
• Electrically tuned helicity of room-temperature valley-polarized electroluminescence was achieved on flexible substrates.

Conclusions:

• Strain engineering in transition metal dichalcogenide monolayers is a viable strategy for room-temperature chiral light sources.
• This work provides a new pathway for practical chiral LEDs for quantum information processing.
• The developed technology allows for electrical tuning of optical helicity at room temperature.