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Ultra-Narrow Linewidth Photo-Emitters in Polymorphic Selenium Nanoflakes
Naveed Hussain1,2,3,4, Shehzad Ahmed5, Hüseyin U Tepe6
1Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610054, China.
Small (Weinheim an Der Bergstrasse, Germany)
|October 17, 2022
Summary
Researchers developed ultra-narrow linewidth photo-emitters (ULPs) in selenium nanoflakes (SeNFs) that function at room temperature. This breakthrough in 2D materials offers significantly narrower emission than previously achieved, paving the way for advanced optical applications.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- State-of-the-art 2D materials exhibit limitations in photoluminescence (PL), including narrow spectral coverage, broad linewidths, and poor room-temperature (RT) functionality.
- Developing efficient and stable photo-emitters for visible to near-infrared (NIR) wavelengths at RT remains a significant challenge in materials science.
Purpose of the Study:
- To report the synthesis and characterization of ultra-narrow linewidth photo-emitters (ULPs) in polymorphic selenium nanoflakes (SeNFs).
- To investigate the underlying mechanisms responsible for the enhanced photoluminescence properties at room temperature.
Main Methods:
- Synthesis of selenium nanoflakes (SeNFs) using a hot-pressing strategy.
- Characterization of photoluminescence properties, including spectral coverage, linewidth (Γ), and coherence time (τc).
- Employing theoretical and experimental methods to analyze crystal structure, phase transitions, and strain effects.
Main Results:
- Achieved RT ULPs across visible to NIR wavelengths in SeNFs.
- NIR emitters demonstrated ultra-narrow linewidths (Γ = 330 ± 90 µeV at 300 K, decreasing to 82 ± 70 µeV at 100 K) and long coherence times (τc = 21.3 ps).
- Identified a polymorphic transition from trigonal (t) to orthorhombic (orth) phase in SeNFs, induced by substrate-enforced spatial confinement and thermal expansion, leading to ultra-sharp emission.
Conclusions:
- The study establishes a correlation between crystal symmetry breaking, induced polymorphism, and RT ULPs in SeNFs.
- The findings highlight the potential of SeNFs as a promising material for advanced photonic and optoelectronic devices operating at room temperature.
- The phase change characteristics and strain engineering offer new avenues for tuning optical properties in 2D materials.
