N-type and p-type molecular doping on monolayer MoS₂

Area of Science:

• Materials Science
• Condensed Matter Physics
• Surface Science

Background:

• Monolayer molybdenum disulfide (MoS₂) is a promising 2D material for optoelectronics due to its high on/off ratio and transparency.
• Surface doping via molecular adsorption is an effective strategy to tailor MoS₂ properties.
• Systematic studies on the effects of specific adsorbates like F₄TCNQ, PTCDA, and tetracene on MoS₂ are lacking.

Purpose of the Study:

• To systematically investigate the impact of F₄TCNQ, PTCDA, and tetracene adsorption on the electronic and optical properties of monolayer MoS₂.
• To elucidate the mechanisms behind the observed changes using theoretical calculations.

Main Methods:

• Density Functional Theory (DFT) calculations were employed to model the interactions between MoS₂ and the chosen molecules.
• Analysis of electronic band structure and optical spectra was performed.

Main Results:

• Adsorption of F₄TCNQ and PTCDA induces p-type semiconducting behavior in MoS₂.
• Tetracene adsorption results in n-type semiconducting behavior.
• New energy levels near the band edges reduce the bandgap of MoS₂.
• F₄TCNQ and PTCDA introduce new optical absorption peaks at 950 nm and 850 nm, respectively.
• Tetracene modifies the optical spectrum primarily in the ultraviolet region.

Conclusions:

• Molecular adsorption of F₄TCNQ, PTCDA, and tetracene can effectively tune the electronic (p-type or n-type) and optical properties of monolayer MoS₂.
• These findings provide a theoretical basis for designing MoS₂-based optoelectronic devices with tailored functionalities.
• The theoretical predictions align well with experimental observations.