ENGINEERING INTERMEDIATE BAND MATERIALS BASED ON METAL-DOPED CHALCOGENIDE COMPOUNDS BY QUANTUM MECHANICAL CALCULATIONS

摘要

In this work we present Density Functional Theory calculations (at the standard theory level and beyond) for metal-containing chalcogenide compounds derived from the chalcopyrite CuGaS_2 and the spinel MgIn_2S_4. The purpose of the work is to develop a material which can be used to create a more efficient photovoltaic solar cell. This material must have a partially filled band inside the band-gap of an appropriate host semiconductor.For chalcopyrite alloy materials we have previously made ab-initio calculations using the Density Functional formalism in the Generalized Gradient Approach for different metals as Ti, V, Cr, and Mn substituting for Ga. For the Ti and Chromium cases, the observation of an intermediate band seems promising, so we have made now further calculations using two more advanced methods which handle more accurately the electron correlation and exchange effects. For Indium thiospinel materials with Vanadium as susbtituent we present here the first standard DFT calculations, showing that this compound is also a good intermediate band material candidate.