Study of Ternary Compounds XYZ2 X Cu Ag Au Y Al Ga In and Z S Se Te for Thermoelectric and Photovoltaic applications using First Principles Method

Abstract

Abstract: newlineTechnological advancement has brought with it abundant usage of energy. Most of the sources of newlineenergy are fossil fuels which come with serious disadvantages. They may become extinct over newlinetime and can pollute our environment. Therefore, reducing our over dependency on fossil fuel by newlinesearching greener sources of energy is the only way out for sustenance of earth. In this regard newlinecompounds of the type XYZ2(where X=Cu,Ag,Au; Y=Al,Ga,In and Z=S,Se,Te) have been chosen newlineas potential materials for photovoltaic and thermoelectric use. We have used Wien2k code and newlineBoltzTrap code to carry out FPLAPW method within First Principle based DFT to study structural, newlineelectronic, optical and thermoelectric properties. We carried out volume optimisation in the first newlineplace to find the optimised lattice parameters which was then used to make our crystal. From the newlineanalysis of the DOS and bandstructure, we came to the conclusion that XYZ2 compounds are p-type newlinedirect band gap compounds. The band gap was found to be in range 0 to 3.5eV which lies within newlineinfrared and visible range making them suitable for use as photovoltaic materials. Moreover, newlineimaginary part of dielectric function showed sharp peaks in the range. The absorption coefficient newlinevalue was also of significant range. The reflectivity was low in the range. This all makes these newlinematerials suitable for photovoltaic applications. We also carried out analysis of thermoelectric newlineproperties. Figure of Merit of CuAlS2 , CuAlSe2 ,CuAlTe2 , CuGaSe2, CuGaTe2, CuInSe2, CuInTe2 at newlinefixed value of chemical potential were respectively close to unity across temperature range 100K to newline1000K. The high ZT value makes them suitable candidates for use as thermoelectric materials. Our newlineinvestigation on the substituted material CuAlxNi1-xS2 compounds yielded them to be p type gapped newlinematerials with usage as photovoltaic use in infra-red region. Likewise, CuAlxSi1-xS2 was found out newlineto be n type gapped materials. CuAlxZn1-xS2 was found to be p type gapped material with use in the newlinerange 1ev