An improved understanding of efficiency limiting defects in polycrystalline CdTe/CdS solar cells

Author

Rohatgi, A. ; Ringel, S.A. ; Sudharsanan, R. ; Chou, H.C.

Author_Institution

Sch. of Electr. Eng., Georgia Inst. of Technol., Atlanta, GA, USA

fYear

1991

fDate

7-11 Oct 1991

Firstpage

962

Abstract

Efficiency-limiting mechanisms associated with CdS substrates, CdCl₂ treated CdTe films, and Cu/Au contacts were investigated. It was found that thermal treatment prior to CdTe deposition removed the oxygen-related defects from the CdS films. However, it also created nonuniform and Cd deficient CdS surface, resulting in an optimum temperature of 450°C. Growth of CdTe films on the CdS under Te-rich conditions enhanced the interdiffusion between CdTe and CdS and reduced the CdTe bandgap to 1.47 eV, whereas growth of CdTe films under Cd-rich conditions retained the CdTe bandgap at 1.5 eV by reducing the interdiffusion. It was found that use of thinner CdS (1000 Å instead of 2000 Å) films increased the cell efficiency from 9.7% to 10.3% by increasing the J_SC from 22.4 to 24.19 mA/cm²

Keywords

II-VI semiconductors; cadmium compounds; chemical interdiffusion; crystal defects; solar cells; 9.7 to 10.3 percent; CdCl₂; CdS; CdS substrates; CdTe bandgap; CdTe film growth; CdTe-CdS solar cells; Cu-Au contacts; efficiency limiting mechanisms; interdiffusion; oxygen-related defects; polycrystalline solar cells; thermal treatment; Annealing; Copper; Etching; Glass; Gold; Molecular beam epitaxial growth; Photonic band gap; Photovoltaic cells; Substrates; Temperature;

fLanguage

English

Publisher

ieee

Conference_Titel

Photovoltaic Specialists Conference, 1991., Conference Record of the Twenty Second IEEE

Conference_Location

Las Vegas, NV

Print_ISBN

0-87942-636-5

Type

conf

DOI

10.1109/PVSC.1991.169351

Filename

169351