title: Optimization of CdS Buffer Layer for High Efficiency CIGS Solar Cells.
abstract: In present work, effects of the thickness on the structural and optical properties of chemically deposited CdS thin films were investigated. In addition, we fabricated Cu(In, Ga)Se2 solar cells with various thicknesses of CdS buffer layer and optimized the thickness for a high efficiency. When the CdS thin films were thicker, the crystallinity improved but the transmittance decreased. The short-circuit current density (J(sc)) and the fill factor are the major efficiency limiting factors for the CIGS solar cells. As the thickness of the CdS buffer layer, the open-circuit voltage (V(oc)) and the fill factor increased, whereas the J(sc) slightly decreased. The improvement of the fill factor and thus efficiency resulted from larger shunt resistance. For the solar cells without a high resistive intrinsic ZnO layer, the highest efficiency was acquired at the thickness of 89 nm. With further increasing the thickness, the J(sc) decreased significantly, resulting in poor efficiency.
authors.forename: Donguk
authors.initials: D
authors.lastname: Kim
authors.forename: Yong-Jun
authors.initials: YJ
authors.lastname: Jang
authors.forename: Ho-Sung
authors.initials: HS
authors.lastname: Jung
authors.forename: Minha
authors.initials: M
authors.lastname: Kim
authors.forename: Dohyun
authors.initials: D
authors.lastname: Baek
authors.forename: Junsin
authors.initials: J
authors.lastname: Yi
authors.forename: Jaehyeong
authors.initials: J
authors.lastname: Lee
authors.forename: Youngkwan
authors.initials: Y
authors.lastname: Choi