Two-dimensional layered semiconductor/graphene heterostructures for solar photovoltaic applications

Abstract

Schottky barriers formed by graphene (monolayer, bilayer, and multilayer) on 2D layered semiconductor tungsten disulfide (WS2) nanosheets are explored for solar energy harvesting. The characteristics of the graphene-WS2 Schottky junction vary significantly with the number of graphene layers on WS2, resulting in differences in solar cell performance. Compared with monolayer or stacked bilayer graphene, multilayer graphene helps in achieving improved solar cell performance due to superior electrical conductivity. The all-layered-material Schottky barrier solar cell employing WS2 as a photoactive semiconductor exhibits efficient photon absorption in the visible spectral range, yielding 3.3% photoelectric conversion efficiency with multilayer graphene as the Schottky contact. Carrier transport at the graphene/WS2 interface and the interfacial recombination process in the Schottky barrier solar cells are examined.

Recent Progress of Janus 2D Transition Metal Chalcogenides: From Theory to Experiments

“…SHG measurement has become an efficient way to characterize the structure, symmetry, and electronic and optical properties of materials. [98,99] For example, a graphene monolayer with inversion symmetry has no SHG response, i.e., the χ (2) is equal to zero. [100][101][102] The TMD odd layers have a strong SHG due to the absence of inversion symmetry while the SHG of the TMD with even layers is removed due to the inversion symmetry.…”

“…It is clear that the value of the I p /I s ratio of the Janus MoSSe monolayer varies with incident angle, but there is no change for the alloyed MoSSe monolayer, confirming the existence of an out-of-plane dipole in Janus structures. [30] The out-of-plane and in-plane second-order susceptibility ratio χ (2) xxz /χ (2) yzz for the five Janus and alloyed MoSSe samples is shown in Figure 6e. A Janus structure has a χ (2) xxz /χ (2) yzz ratio of ≈10:1, further demonstrating the presence of an out-of-plane dipole.…”

“…Due to their outstanding properties, 2D materials have become a major research focus, with regard to their potential application in novel electronic and optoelectronic devices in the last decade, such as solar cells, light-emitting diodes, field-effect transistors, photodetectors, and lasers. [2][3][4][5][6][7][8] Among these 2D materials, TMDs have attracted considerable attention because of their tunable bandgap, ultrathin thickness, and unique electronic, optical, and mechanical properties. [9][10][11][12][13] In addition, a number of derivatives of 2D materials are emerging, including alloys and 2D van der Waals heterojunctions.…”

Recent Advances in van der Waals Heterojunctions Based on Semiconducting Transition Metal Dichalcogenides

“…[131,147,[149][150][151][152] Shanmugam et al have studied the performance of Schottky barrier solar cells formed by growing graphene layers on WS 2 nanosheets. [135] The photoelectric conversion efficiency of multilayer, bilayer, and monolayer graphene stacked on the WS 2 monolayer can reach 3.3%, 2.9%, and 2.3%, respectively. The power conversion efficiency for WSe 2 /MoS 2 vdWH on Si/SiO 2 substrate is ≈0.2%, and the external quantum efficiency is ≈1.5%, as reported by Furchi et al [136] Gong et al have reported that the power conversion efficiency of the WS 2 /MoSe 2 vdWH prepared through a two-step CVD method is ≈0.12% without any external gates.…”

“…Shanmugam et al [135] WSe 2 /MoS 2 MX 2 /semiconductor Power conversion efficiency ≈ 0.2% External quantum efficiency ≈1.5%…”