Control of point defects in the Cu(In,Ga)Se2 film synthesized at low temperature from a Cu/In2Se3 stacked precursor

• Published in: Electronic materials letters Vol. 12; no. 4; pp. 472 - 478
• Main Authors: Jung, Gwang Sun, Kim, Seungtae, Ko, Young Min, Moon, Sun Hong, Choi, Yong Woo, Ahn, Byung Tae
• Format: Journal Article
• Language: English
• Published: Seoul The Korean Institute of Metals and Materials 01.07.2016; 대한금속·재료학회
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Condensed Matter Physics; Materials Science; Nanotechnology; Nanotechnology and Microengineering; Optical and Electronic Materials; 전자/정보통신공학; point defects; Cu(In,Ga)Se; photoluminescence; antisite defect; Cu vacancy
• ISSN: 1738-8090; 2093-6788
• DOI: 10.1007/s13391-016-4009-9

Low-temperature fabrication of Cu(In,Ga)Se 2 (CIGS) film is essential for flexible CIGS solar cells. A large-grained CIGS film was synthesized with a Se-deficient Cu/In,Ga) 2 Se 3 stacked precursor by reacting at 500 °C in a vacuum and was then subsequently annealing in Se environment. The CIGS solar cell with the as-prepared CIGS film had a poor cell performance due to a very low Ga composition at the CIGS surface. The surface Ga composition was controlled to 0.2 by supplying In, Ga, and Se in a temperature range of 350 to 500 °C. From an analysis of the photoluminescence spectra, we found that the point defects, Se vacancy and In-in-Cu antisite, in the CIGS film were greatly reduced by annealing below 450 °C. The short-circuit current was pronouncedly increased in the CIGS cells. The open-circuit voltage depended on both the Ga composition and Cu composition at the CIGS surface. In particular, a low Cu composition at the CIGS surface was essential for the higher performance solar cells. Our results indicated that CIGSs film synthesized at high temperature must be annealed at 350 °C or below to reduce undesirable point defects.