Extremely Enhanced Photoluminescence in MoS₂-Derived Quantum Sheets.

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Molybdenum disulfide (MoS2) quantum sheets (QSs) possess tunable optoelectronic properties, making them attractive for various applications.
• Current methods for producing MoS2 QSs yield low photoluminescence quantum yields (PLQY), limiting their practical use.
• Existing techniques to enhance PLQY, such as chemical treatment and doping, often require complex equipment and procedures.

Purpose of the Study:

• To develop a simple and effective method for enhancing the photoluminescence quantum yield (PLQY) and intensity of molybdenum disulfide (MoS2) quantum sheets (QSs).
• To investigate the underlying mechanism responsible for the observed photoluminescence enhancement.
• To demonstrate the applicability of the developed method to other transition metal dichalcogenides (TMDs), such as tungsten disulfide (WS2).

Main Methods:

• A novel heat treatment method utilizing a polar solvent was employed to treat MoS2 QSs.
• The photoluminescence quantum yield (PLQY) and photoluminescence (PL) intensity of the treated MoS2 QSs were measured at room temperature.
• The method was also applied to tungsten disulfide (WS2) QSs to assess its general effectiveness.

Main Results:

• The heat treatment significantly improved the PLQY of MoS2 QSs, reaching an absolute value of 18.5%.
• The PL intensity of the treated MoS2 QSs was enhanced by a factor of 64 compared to untreated samples.
• The enhancement in PL is attributed to the oxidation of the edges of the QSs, which passivates defects and promotes radiative recombination pathways.

Conclusions:

• A facile heat treatment in a polar solvent effectively enhances the photoluminescence of MoS2 QSs and WS2 QSs.
• The observed PL enhancement is linked to edge oxidation, which facilitates radiative emission over non-radiative processes.
• This work presents a promising strategy for improving the optoelectronic performance of transition metal dichalcogenide quantum sheets.