Promoting the optoelectronic and nonlinear optics properties of MoS2 nanosheets via metal Al anchoring

Abstract

Molybdenum disulfide (MoS2) has attracted much attention in the field of optoelectronic materials due to its stability and adjustable bandgap structure. However, improving the optoelectronic properties of MoS2 is still a challenging research. Herein, Al doped MoS2 (AMS) films were prepared by a simple single-step magnetron sputtering method. The bonding modes of Al implantation and auxiliary MoS2 were investigated by adjusting metal Al anchoring. The successful synthesis of AMS films was confirmed by the analysis of X-ray diffraction and X-ray photoelectron spectroscopy measurements to investigate the diffraction peaks of Al and Al2S3 and the valence electron structures of Al3+. Compared to MoS2, the A1g Raman peaks of AMS films are slightly blue-shifted, and the peak positions of both Mo3d and S2p are slightly shifted towards higher binding energies. This is attributed to the surface plasmon resonance effect produced by Al doping resulting in a large amount of electron transfer to the conduction band (CB) of MoS2. In addition, the density functional theory calculations reveal that Al doping of MoS2 results in a higher concentration of electrons in CB of MoS2, the band gap of MoS2 can be adjusted by changing the doping concentration of Al. The Z-scan results illustrated that MoS2 was converted from saturable absorption to reverse saturable absorption (RSA) by adjusting the sputtering power of Al. This is attributed to the fact that Al doping increases the electron concentration in the CB of MoS2, which promotes the RSA of the excited states and doping energy levels of AMS films. The values of the nonlinear absorption coefficients of AMS films are 2–5 times higher than those of MoS2, which significantly improves the nonlinear absorption performance of MoS2. The carrier relaxation process and kinetic mechanism of AMS films were investigated by transient absorption spectroscopy, moderate doping of Al can effectively improve the carrier lifetime. This implies that AMS films have good optoelectronic properties and have a wide application potential in optoelectronic devices.