Materials Design of Spinodal Nanodecomposition in CuIn1-xGaxSe2for High-Efficiency Solar Energy Conversion

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 CuIn 1- x Ga x Se 2 (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 CuInSe 2 and CuGaSe 2 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.