Marie-Christine Record
Aix-Marseille University, France
Title: Investigation of the CuIn1-xAlxSe2 structure-properties relationships by coupling density functional and Bader’s theories
Biography
Biography: Marie-Christine Record
Abstract
For three decades density functional theory (DFT) has imposed itself as an accurate quantum method to investigate materials properties. In parallel, developments of density based descriptors such as Bader’s quantum theory of atoms in molecules (QTAIM) brought new insights into the chemical bonding of materials. The ternary Cu-based chalcopyrite compound, CuInSe2 (CIS), is an interesting material as solar cell absorber layer due to its low cost, high absorption coefficient, excellent optical and electrical properties. Many approaches have been adopted to improve its energy conversion efficiency. However, its narrow band gap and the scarcity and expensiveness of indium constrain its large-scale development. Replacing indium by the abundant and inexpensive aluminum to form the quaternary CuIn1-xAlxSe2 (CIAS), has been considered as a promising alternative with few changes in physical and chemical properties. In this work, we investigated by DFT calculations the structural, electronic and optical properties of CuIn1-xAlxSe2, for various “x” from 0 to 1, and determined the optimal substituting percentage. Moreover, in current PV cells, strains originating from the lattice mismatch between the PV materials and the substrates inevitably influence the optical performances, we calculated the band gap and optical properties for the optimal alloy subjected to biaxial strains. In the aim to unravel the deep relationship between bond interactions and optical properties, a detailed investigation of topological properties based on the electron density has been conducted as strain is applied.