Excitons and Trions in MoS₂ Quantum Dots: The Influence of the Dispersing Medium

Abstract

Single-layer MoS 2 has been reported to exhibit strong excitonic and trionic signatures in its photoluminescence (PL) spectra. Here, we report that the emission spectra of MoS 2 QDs strongly depend on the dielectric constant of the solvent and the relative difference in the electronegativity between the solvent and QDs. Due to the difference in electronegativity, electrons are either added to the QD or withdrawn from it. Consequently, depending upon the dielectric permittivity and the electronegativity of the surrounding medium, the signature peaks of excitons and trions exhibit a significant change in the PL spectra of MoS 2 QDs. Our findings are helpful to understand the effect of the surrounding environment on the optical properties of QDs and the importance of the selection of solvent since MoS 2 QDs are potential candidates for valleytronics applications.

Untangling the intertwined: metallic to semiconducting phase transition of colloidal MoS2 nanoplatelets and nanosheets

“…13 Recently, the lateral size of 2D TMDCs has received increasing attention in catalytic and photonic research. 14,15 On the one hand, the influence of edge states increases for small lateral sizes of 2D TMDC layers. While these states are found in the band gap and are essential for catalysis, [16][17][18][19] they also suppress photoluminescence (PL) by non-radiative recombination in the structures.…”

Untangling the Intertwined: Metallic to Semiconducting Phase Transition in Colloidal MoS2 Nanoplatelets and Nanosheets

“…13 Recently, the lateral size of 2D TMDCs has received increasing attention in catalytic and photonic research, as it additionally governs the optoelectronic properties of the materials. 14,15 On the one hand, the influence of edge states increases for small lateral sizes of 2D TMDC layers. While these states are found in the band gap and are essential for catalysis, [16][17][18][19] they also suppress photoluminescence (PL) by non-radiative recombination in the structures.…”

pH-Dependent Photophysical Properties of Metallic Phase MoSe2 Quantum Dots

“…Also, the optical energy band structure of the TMDs- m QDs was reported to be predominantly affected by edge oxidation [ 15 ]. Because the defect and the edge oxidation of atomically thin TMDs- m QDs strongly depends on the environmental conditions [ 16 , 17 , 18 , 19 ], to study the photophysical properties as changing the pH of solution and the size relating to defects is essential for the practical applications.…”