Regensburg 2010 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 35: New Materials: Optoelectronic and Photovoltaic Applications

HL 35.2: Talk

Wednesday, March 24, 2010, 09:45–10:00, H13

Alternative bufferlayers for CIGS solarcells. — •A. Beleanu, T. Gruhn, C.G.F. Blum, B. Balke, and C. Felser — Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg - University, Mainz, Germany

Cadmium sulfide is a highly efficient buffer layer material in Cu(In,Ga)(S,Se2) [CIGS] solar devices [1], but for environmental reasons and possible gains in efficiency there is a great interest in replacing CdS by a cadmium-free alternative buffer layer. Using standard density functional theory (DFT) methods possible candidates like LiZnP and LiCuS have been proposed as alternative buffer layers. The experimental verificaition of the DFT results was quite challangeing due to the fact that LiCuS was an unknow and completely new material. In a first step, we tried to synthesised LiCuS through solid state reactions in a corrund crucible. After optimizing the parameters and successfully synthesising the material its properties were investigated. In a second step, huge amounts of LiCuS and LiZnP were synthesised and pressed using Spark Plasma Sintering as 3 inch targets. LiCuS and LiZnP films were grown by radio-frequency magnetron sputtering from these target and their properties as an alternative buffer layer in CIGS solar cells were investigated. The 1:1:1 stoichiometry of the films was delivered from in-situ XPS measurements. Absorption measurements show a band gap of ≈ 2.0 eV which is in good agreement with the theoretical estimates. [1]T. J. Coutts, Thin Solid Films, 90 (1982) 451-460. This work was financially supported by the BMU project comCIGS.