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Study of exciton recombination process is of great significance for the optoelectronic device applications of two-dimensional transition metal chalcogenides (TMDCs). This research investigated the decoupling MoS

Recently, two-dimensional (2D) van der Waals heterostructures (vdWHs) have exhibited emergent electronic and optical properties due to their peculiar phonons and excitons, which lay the foundation for the development of photoelectronic devices. The dielectric environment plays an important role in the interlayer coupling of vdWHs. Here, we studied the interlayer and extra-layer dielectric effects on phonon and exciton properties in WS

Angle-resolved polarized (ARP) Raman spectroscopy can be utilized to characterize the Raman modes of two-dimensional layered materials based on crystal symmetry or crystal orientation. In this paper, the polarization properties of

Study of exciton recombination process is of great significance for the optoelectronic device applications of two-dimensional transition metal chalcogenides (TMDCs). This research investigated the decoupling MoS2 structures by photoluminescence (PL) measurements. First, PL intensity of the bilayer MoS2 (BLM) is about twice of that of the single layer MoS2 (SLM) at low temperature, indicating no transition from direct bandgap to indirect bandgap for BLM due to the decrease of interlayer coupling which can be shown by Raman spectra. Then, the localized exciton emission appears for SLM at 7 K but none for BLM, showing different exciton localization characteristics. The PL evolution with respect to the excitation intensity and the temperature further reveal the filling, interaction, and the redistribution among free exciton states and localized exciton states. These results provide very useful information for understanding the localized states and carrier dynamics in BLM and SLM.

Amorphous–microcrystalline MoS2 thin films are fabricated using the sol-gel method to produce MoS2/Si-based solar cells. The generation mechanisms of the S-shaped current density–voltage (J–V) curves of the solar cells are analyzed. To improve the performance of the solar cells and address the problem of the S-shaped J–V curve, a MoS2 film and a p+ layer are introduced into the front and back interfaces of the solar cell, respectively, which leads to the formation of a p–n junction between the p-Si and the MoS2 film as well as ohmic contacts between the MoS2 film and the ITO, improving the S-shaped J–V curve. As a result of the high doping characteristics and the high work function of the p+ layer, a high–low junction is formed between the p+ and p layers along with ohmic contacts between the p+ layer and the Ag electrode. Consequently, the S-shaped J–V curve is eliminated, and a significantly higher current density is achieved at a high voltage. The device exhibits ideal p–n junction rectification characteristics and achieves a high power-conversion efficiency (CE) of 7.55%. The findings of this study may improve the application of MoS2 thin films in silicon-based solar cells, which are expected to be widely used in various silicon-based electronic and optical devices.