Title :
High-efficiency cadmium-free Cu(In,Ga)Se2 thin-film solar cells with chemically deposited ZnS buffer layers
Author :
Nakada, Tokio ; Furumi, Keisuke ; Kunioka, Akio
Author_Institution :
Dept. of Electr. Eng. & Electron., Aoyama Gakuin Univ., Tokyo, Japan
fDate :
10/1/1999 12:00:00 AM
Abstract :
Cadmium-free Cu(In,Ga)Se2 (CICS) thin-film solar cells with a MgF2/ZnO:Al/CBD-ZnS/CIGS/Mo/SLG structure have been fabricated using chemical bath deposition (CBD)-ZnS buffer layers and high-quality CICS absorber layers grown using molecular beam epitaxy (MBE) system. The use of CBD-ZnS, which is a wider band gap material than CBD-CdS, improved the quantum efficiency of fabricated cells at short wavelengths, leading to an increase in the short-circuit current. The best cell at present yielded an active area efficiency of 16.9% which is the highest value reported previously for Cd-free CIGS thin-film solar cells. The as-fabricated solar cells exhibited a reversible light-soaking effect under AM 1.5, 100 mW/cm2 illumination. This paper also presents a discussion of the issues relating to the use of the CBD-ZnS buffer material for improving device performance
Keywords :
II-VI semiconductors; copper compounds; energy gap; gallium compounds; indium compounds; liquid phase deposition; molecular beam epitaxial growth; semiconductor epitaxial layers; semiconductor growth; solar cells; ternary semiconductors; 16.9 percent; Cu(InGa)Se2-ZnS; absorber layers; active area efficiency; band gap; chemical bath deposition; device performance; molecular beam epitaxy; quantum efficiency; reversible light-soaking effect; short-circuit current; thin-film solar cells; Buffer layers; Chemicals; Molecular beam epitaxial growth; Optical buffering; Photonic band gap; Photovoltaic cells; Sputtering; Transistors; Zinc compounds; Zinc oxide;
Journal_Title :
Electron Devices, IEEE Transactions on
