Device Physics of Thin-Film Polycrystalline Cells and Modules: Annual Subcontract Report, 6 December 1994 - 5 December 1995

    Research output: NRELSubcontract Report


    This report describes the work on a number of projects carried out at both the cell and the module level during the past year. We investigated the effects of CdS thickness in collaboration with six CdTe cell-fabrication laboratories; there appears to be a critical thickness, between 500 and 1000 Angstroms depending on fabrication process, below which junction quality is degraded. Our experimentaland modeling project showed that conduction-band offsets less than about 0.3 eV have little effect on the performance of a CuInSe2 (CIS) or CdTe cell under the traditional assumption that the absorber material accounts for most of the depletion region. The work in several other cell projects included the role of Ga distribution in Cu1-xGaxSe2 (CIGS) cells, changes that occur in some cells overtime, optical characterization of commonly used CdTe substrates and front contacts, and comparative characterization of CIGS cells where identical absorbers were combined with variations in window fabrication. Our work on the primary module-characterization project developed the successful use of chopping-frequency variation in a scanning beam to separate photocurrent and shunting problemsaffecting individual cells of an encapsulated module. Other module projects included modifications in analysis required by the typical module-cell geometry, the practical effect of nonuniformities in light intensity or cell temperature, and the advantages and pitfalls of forward bias across a module during a light scan.
    Original languageAmerican English
    PublisherNational Renewable Energy Laboratory (NREL)
    Number of pages35
    StatePublished - 1996

    Bibliographical note

    Work performed by the Department of Physics, Colorado State University, Fort Collins, Colorado

    NREL Publication Number

    • NREL/TP-451-21586


    • CIGS
    • CIS
    • photovoltaics (PV)
    • polycrystalline
    • thin film


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