Development of an all-metal thick film cost effective metallization system for solar cells. Final report, May 1980-January 1983

Technical Report · Thu Dec 01 00:00:00 EST 1983

DOI:https://doi.org/10.2172/5266522· OSTI ID:5266522

Ross, B.; Parker, J.

Properties of copper pastes did not reproduce earlier results in rheology and metallurgy. Electrodes made with pastes produced under the previous contract were analyzed and raw material characteristics were compared. A needle-like structure was observed on the earlier electroded solar cells, and was identified as eutectic copper-silicon. Experiments were conducted with variations in paste parameters, firing conditions, including gas ambients, furnace furniture, silicon surface and others to improve performance characteristics. Improved adhesion with copper pastes containing silver fluoride, as well as those containing fluorocarbon powder was obtained. Front contact experiments were done with silver fluoride activated pastes on bare silicon, silicon oxide and silicon nitride coated silicon wafers. Adhesion of pastes with AgF on silicon nitride coated wafers was good, but indications were that all cells were shunted and the conclusion was that these systems were unsuitable for front contacts. Experiments with aluminum back surfaces and screened contacts to that surface were begun. Low temperature firing tended to result in S shaped IV curves. This was attributed to a barrier formed at the silicon-copper interface. A cooperative experiment was initiated on the effect of heat-treatments in various atmospheres on the hydrogen profile of silicon surfaces. Contact theory was explored to determine the role of various parameters on tunneling and contact resistance. Data confirm that the presence of eutectic Al-Si additions are beneficial for low contact resistance and fill factors in back contacts. Copper pastes with different silver fluoride additions were utilized as front contacts at two temperatures. Data shows various degrees of shunting. Finally, an experiment was run with carbon monoxide gas used as the reducing ambient during firing.

• Research Organization: Bernd Ross Associates, San Diego, CA (USA)
• DOE Contract Number: NAS-7-100-955688
• OSTI ID: 5266522
• Report Number(s): DOE/JPL/955688-82/10; ON: DE84008241
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
SILICON SOLAR CELLS
ELECTRIC CONTACTS
COPPER
FILMS
HEAT TREATMENTS
HYDROGEN
SILVER FLUORIDES
DIRECT ENERGY CONVERTERS
ELECTRICAL EQUIPMENT
ELEMENTS
EQUIPMENT
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
METALS
NONMETALS
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
SILVER COMPOUNDS
SOLAR CELLS
SOLAR EQUIPMENT
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
140501* - Solar Energy Conversion- Photovoltaic Conversion