报告题目：Chalcogenides Materials for Thermoelectricity, Solar Cells and Radiation Detectors
Chalcogenides compounds (CGC) form a very large and versatile group of materials, in which one can distinguish between the mono-, di-, and tri-chalcogenides. In these compounds all ions are four-fold coordinated; the chemical bonds between them are usually strongly covalent. The crystal structure of the chalcogenide compounds offers a possibility for partial or complete substitution of cation or anion groups, i.e. formation of solid solutions, whose properties can be significantly different from those of pure compounds. The crystal structure of chalcogenides depends on their composition and can be cubic (CdS), trigonal (CdI2) etc. CGC are widely used for solar cell, radiation detectors and thermoelectric applications, since they can be grown in the form of thin films. The I-III-VI2ternary semiconductors with the chalcopyrite structure (e.g. CuGaS2, CuInS2etc.) have been shown as very suitable materials for the solar panels, since they can be grown as thin films which efficiently increases the surface exposed to sunlight. Moreover, the Cu(In,Ga)(Se,S)2- based solar elements already challenge the dominance of the traditional silicon solar panels. The band structure parameters of these materials are influenced by intrinsic defects forming the additional trapping levels within the host’s band gap. Such defects can significantly change the optical properties of a material, considerably enhance its optical absorption and, therefore, they play a principal role for the optoelectronic and photovoltaic applications. The complex approach, which includes theoretical analysis based on the DFT methods supported by the optical experimental studies of the absorption near the band gap spectral range, is a very powerful tool for predicting the optoelectronic features of the materials used for the solar panels. It also allows for modelling the defects properties and their influence on the host’s properties .
Nowadays considerable progress has been achieved in the development of experimental methods of the