Process Development and Basic Studies of Electrochemically Deposited CdTe-Based Solar Cells; Annual Technical Report, Phase II, 16 May 1999-13 May 2000

This project, carried out at the Colorado School of Mines, addresses long-term research and development issues related to polycrystalline thin-film solar cells. Our general research approach is based on combining activities aimed at improving cell performance and stability with activities aimed at increasing our fundamental understanding of the properties of materials making up the cells: CdTe, CdS, multilayer back-contact, and transparent conducting oxide (TCO) from contact. We emphasize the relation between structural and electronic materials properties and various processing procedures, as well as the microscopic mechanisms responsible for the cell performance and its degradation. Section 1 presents studies of degradation under stressing of the cells with differently processed CdTe and different back contents. Section 2 presents studies of deep traps in the electrodeposited (ED) CdTe cells performed in collaboration at NREL. Section 3 reports studies of the spectral dependencies of photocurrent, and their spatial distribution over the cross-section of the ED CdTe cells were performed using near-field scanning optical microscopy (NSOM). Section 4 discusses the impedance spectroscopy of CdTe and CdS thin films. Section 5 presents studies of band spectrum and electron scattering in transparent conducting oxides. Appendices present data on personnel involved in the studies, laboratory improvements, and publications