Defect formation energetics at the grain boundary in CuInSe2 using first-principles calculations

Abstract

We investigated defect formation energetics at the grain boundary (GB) in CuInSe2 (CIS) using first-principles calculations. We focused on the (112)[11̄0] Σ3 twin GB in CIS because this GB is known to be easily formed in CIS. Formation energies and accompanied atomic relaxation of neutral Cu, In, and Se vacancies (VCu 0, VIn 0, and VSe 0), the In antisite defect (InCu 0), and the Schottky defect (InCu2+ + 2VCu -) were investigated in the bulk and GB. We found that CIS shows characteristic atomic relaxation after vacancy formation, and VCu 0 is the most energetically favorable defect in both the bulk and the GB. Furthermore, we found that (112)[11̄0] Σ3 twin GB does not promote the formation of the Cu vacancy under all conditions, whereas it relatively promotes the formation of the Se vacancy under metal-rich conditions. © 2014 The Ceramic Society of Japan.