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Boosting quantum yields in two-dimensional semiconductors via proximal metal plates
Yongjun Lee1, Johnathas D'arf Severo Forte2, Andrey Chaves2,3
1Department of Energy Science, Sungkyunkwan University, Suwon, 16419, Republic of Korea.
Nature Communications
|December 8, 2021
Summary
Researchers enhanced light emission in 2D materials by screening exciton-exciton interactions. Using a gold film and hexagonal boron nitride, they boosted quantum yield by tenfold, paving the way for efficient 2D light emitters.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Optics
Background:
- Monolayer transition metal dichalcogenides (1L-TMDs) are promising 2D semiconductors for quantum photonic devices.
- Short exciton lifetimes and strong exciton-exciton interactions limit light emission efficiency in 1L-TMDs.
Purpose of the Study:
- To investigate methods for screening exciton-exciton interactions in 1L-TMDs.
- To enhance the quantum yield and reduce exciton-exciton annihilation (EEA) in 1L-WS2.
Main Methods:
- Utilized an ultra-flat gold (Au) film substrate separated by hexagonal boron nitride (hBN) multilayers.
- Employed time-resolved optical measurements to confirm reduced EEA rates.
- Developed a theoretical model for screened dipole-dipole interactions.
Main Results:
- Achieved effective screening of exciton-exciton interactions in 1L-WS2 by converting dipole-dipole to quadrupole-quadrupole interactions.
- Observed a significant enhancement in quantum yield (by an order of magnitude).
- Confirmed a reduced exciton-exciton annihilation (EEA) rate.
Conclusions:
- Metallic screening via Au/hBN substrates effectively suppresses detrimental exciton-exciton interactions.
- Engineered EEA processes in 2D materials offer a practical route to high-efficiency 2D light emitters.
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