Materials Design of Spinodal Nanodecomposition in CuIn1-xGaxSe2 for High-Efficiency Solar Energy Conversion

Abstract

Based on the first-principles calculations within the self-interaction-corrected local density approximation, we propose a materials design for high efficiency photovoltaic solar cells. By using the Korringa–Kohn–Rostoker coherent potential approximation method, the electronic structure and mixing energy of CuIn1-xGaxSe2 (CIGS) are calculated. It is found that (1) CIGS has positive and convex mixing energy; thus, it has a tendency towards spinodal nano-decomposition, and (2) the band alignment between CuInSe2 and CuGaSe2 is type II. Based on these findings, it is pointed out that efficient electron–hole separation and multiexciton effect upon photoexcitation can be expected in the spinodal decomposed CIGS for realizing high-efficiency energy conversion.