On the unique temperature-dependent interplay of a B-exciton and its trion in monolayer MoSe2

Banswar, D and Sahu, RR and Srivatsava, R and Hassan, MS and Singh, S and Sapra, S and Das Gupta, T and Goswami, A and Balasubramanian, K (2023) On the unique temperature-dependent interplay of a B-exciton and its trion in monolayer MoSe2. In: Nanoscale .

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Abstract

Plasmonics in metal nanoparticles can enhance their near field optical interaction with matter, promoting emission into selected optical modes. Here, using Ga nanoparticles with carefully tuned plasmonic resonance in proximity to MoSe2 monolayers, we show selective photoluminescence enhancement from the B-exciton and its trion with no observable A-exciton emission. The nanoengineered substrate allows for the first direct experimental observation of the B-trion binding energy in semiconducting monolayers. Using temperature-dependent photoluminescence measurements, we show the following features of the MoSe2 B-exciton family: (i) the trion binding energy has an observable temperature dependence with a decreasing trend towards low temperatures and (ii) the exciton-trion emission ratio varies non-monotonically with temperature with a steep increase in the trion emission at lower temperatures. Using detailed models, we identify the particle size required for selective excitation and describe the underlying physical processes. This opens newer avenues for selectively promoting excitonic species and tuning the effective particle lifetimes in monolayer semiconductors. These results demonstrate the excellent plasmonic properties of Ga nanoparticles, which along with facile processing techniques makes it an attractive alternative to the prevalent noble metal plasmonics having applications in flexible/stretchable materials and textiles. © 2024 The Royal Society of Chemistry.

Item Type:	Journal Article
Publication:	Nanoscale
Publisher:	Royal Society of Chemistry
Additional Information:	The copyright for this article belongs to author
Keywords:	Binding energy; Gallium; Layered semiconductors; Metal nanoparticles; Molybdenum compounds; Monolayers; Particle size; Photoluminescence; Plasmonics; Precious metals; Selenium compounds; Temperature distribution, Lows-temperatures; Near fields; Optical interactions; Optical modes; Photoluminescence enhancement; Plasmonic resonances; Plasmonics; Temperature dependent; Trion; Trion binding energy, Excitons
Department/Centre:	Others
Date Deposited:	01 Mar 2024 10:28
Last Modified:	01 Mar 2024 10:28
URI:	https://eprints.iisc.ac.in/id/eprint/84049

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