Chromium Thiophosphate - CrPS₄- Investigated in Bulk and Few-layers Form

Layered materials, also called two dimensional (2D) materials are in center of interest, since exfoliation of graphite into monolayer, that is called graphene nowadays. 2D materials belong to large family of anisotropically built compounds. They have strong, covalent bonds within a layer and between them there are only weak van der Waals interactions. This structure enables obtaining molecularly thin sheets. Such a decrease of dimensionality has a great impact on properties, which vary strongly with the number of atomic layers.

As graphene application in electronic is hindered by its zero band gap, layered semiconductors are studied as candidates for building future devices. So far, many Transition Metal Dichalcogenides (TMDs), such as MoS₂, MoSe₂, WS₂, WSe₂, were intensively investigated, but to meet rising demands, new families of 2D semiconductors are studied. One of them are transition metal thiophosphates, with formula MPS_x, where x=3 or 4. For example, bulk crystals of CrPS₄ - chromium thiophosphate were examined in the past for application i.e. in lithium batteries. Nowadays, this compound is once again in scientific interest due to its optical anisotropic properties and possibility to obtain and study its few- and monolayer systems.

Poster will present vapor transport synthesis (furnace method) of bulk crystals of CrPS₄, structure and composition analysis by different technics. For example Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (SEM/EDX), Powder X-Ray Diffraction (PXRD) and Raman spectroscopy experiments were performed. Optical properties, such as band gap and optical transitions were investigated by Solid State UV-VIS Spectroscopy, PhotoAcoustic Spectroscopy (PAS) and Modulated Spectroscopy (MS). Later, bulk crystals of chromium thiophosphate (CrPS₄) were liquid exfoliated to few layers system and photoconductivity measurements were involved to check photoactive properties, both bulk crystals and films from exfoliated material.

Acknowledgments:

This work was supported by the European Comission via the Marie-Sklodowska Curie action Phonsi (H2020-MSCA-ITN-642656)