Tolerance of Three-Stage CIGS Deposition to Variations Imposed by Roll-to-Roll Processing: Phase II Annual Report, May 2003 – May 2004

NOTICE This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or any agency thereof. Executive Summary Co-evaporation of CuIn x Ga 1-x Se 2 (CIGS) via two-stage and three-stage processes has been used in a variety of laboratories throughout the world to produce small-area devices with efficiencies greater than 15%. Thus, these deposition methods have come to be viewed as laboratory standards for the formation of CIGS absorbers used in respective photovoltaic devices. Although quite successful and relative easy to implement on a small R&D scale, scale-up to a commercially viable level proves to be rather challenging, as a number of conditions are encountered during continuous manufacturing that differ from the laboratory process. Such differences include both those imposed by continuous processing of moving substrates, and those implemented to decrease costs and increase throughput. It is therefore beneficial to understand the tolerance of the established laboratory processes to variations in deposition procedures. Research under this program consists of four basic parts to examine the tolerance of the established laboratory process to variations in deposition procedures: 1. Setting up the National Renewable Energy Laboratory (NREL)-developed three-stage CIGS laboratory process in a bell jar. (Phase I) 2. Characterizing the GSE roll-to-roll production chambers and device finishing steps in terms of the variables important to the laboratory processes. (Phase II) 3. Using the bell jar system to step incrementally from the NREL process to the conditions experienced by a sample during manufacturing, and characterizing the resulting films and devices. (Phase II and III) 4. Applying the process sensitivity information gained from the bell jar system to the production systems to realize improved device performance, yield, and process robustness. (Phase II and III) Work during Phase …