Mechanistic Insight to the Chemical Treatments of Monolayer Transition Metal Disulfides for Photoluminescence Enhancement

Abstract

There is a growing interest in obtaining high quality monolayer transition metal disulfides (TMDSs) for optoelectronic device applications. Surface chemical treatments using a range of chemicals on monolayer TMDSs have proven effective to improve their photoluminescence (PL) yield. However, the underlying mechanism for PL enhancement by these treatments is not clear, which prevents a rational design of passivation strategies. In this work, a simple and effective approach to significantly enhance PL of TMDSs is demonstrated by using a family of cation donors, which we show to be much more effective than commonly used p-dopants which achieve PL enhancement through electron transfer. We develop a detailed mechanistic picture for the action of these cation donors and demonstrate that one of them, Li-TFSI (bistriflimide), enhances the PL of both MoS2 and WS2 to a level double that compared to the widely discussed and currently best performing super acid H-TFSI treatment. In addition, the ionic salts used in chemical treatments are compatible with a range of greener solvents and are easier to handle than super-acids, which provides the possibility of directly treating TMDSs during device fabrication. This work sets up rational selection rules for ionic chemicals to passivate TMDSs and increases the potential of TMDSs in practical optoelectronic applications.

36 pages, 18 figures, 2 tables

References in corpus (5)

• Towards Intrinsic Charge Transport in Monolayer Molybdenum Disulfide by Defect and Interface Engineering
• Electrical suppression of all nonradiative recombination pathways in monolayer semiconductors
• The bright side of defects in MoS${}_2$ and WS${}_2$ and a generalizable chemical treatment protocol for defect passivation
• Exciton Trapping Is Responsible for the Long Apparent Lifetime in Acid-Treated MoS2
• Understanding Variations in Circularly Polarized Photoluminescence in Monolayer Transition Metal Dichalcogenides

Cited by in corpus (4)

• Enhanced Light-Matter Interaction in Two-Dimensional Transition Metal Dichalcogenides
• Monolayer WS${}_2$ electro- and photo-luminescence enhancement by TFSI treatment
• Photophysical comparison of liquid and mechanically exfoliated WS${}_2$ monolayers
• Localized Gradual Photomediated Brightness and Lifetime Increase of Superacid Treated Monolayer MoS${}_2$