AVS 52nd International Symposium
    Thin Films Monday Sessions
       Session TF+EM-MoM

Paper TF+EM-MoM5
Surfactant-assisted Growth of CdS Thin Films for Photovoltaic Applications

Monday, October 31, 2005, 9:40 am, Room 306

Session: Thin Films for Photovoltaic and Energy Applications
Presenter: C.L. Perkins, National Renewable Energy Laboratory
Authors: C.L. Perkins, National Renewable Energy Laboratory
F.S. Hasoon, National Renewable Energy Laboratory
Correspondent: Click to Email
A common non-ionic surfactant, Triton X-100, was used to modify the chemical bath deposition (CBD) of CdS "buffer" layers on Cu(In,Ga)Se@sub 2@ (CIGS) thin films. X-ray photoelectron spectroscopy and Auger electron spectroscopy data demonstrate that films produced with the surfactant have about the same levels of impurities as films grown without it. It was found that Triton X-100 allowed the use of CdS layers that were 3-4 times thinner than those used normally in high efficiency CIGS-based devices, with no loss in cell performance. For these thin CdS layers and relative to devices made without the surfactant, average absolute cell efficiencies were increased from 10.5% to 14.8%, or by a relative 41%. Visual inspection of the CdS depositions reveals one possible mechanism of the surfactant's effects: bubbles that form and adhere to the CIGS surface during the chemical bath deposition are almost completely eliminated with the addition of the TX-100. Thus, pinholes and thin areas in the CdS layers caused by poor wetting of the substrate surface are sharply reduced, leading to large increases in the open circuit voltage in devices produced with the surfactant.