A low cost roll-to-roll amorphous silicon solar cell manufacturing system using a novel hollow cathode plasma deposition technique
B. Boardman, T. Casserly, D. Upadhyaya
Sub-One Technology, US
Keywords: Hollow cathode, bi-polar, amorphous silicon, solar cell, roll-to-roll, steel foil substrate
Abstract:Sub-One Technology has invented, patented and commercialized a chamber-less hollow cathode plasma technology to deposit films using a variety of materials at deposition rates which are up to 20 times faster than traditional PVD and CVD technologies. Currently, this technology is available to deposit a thick (up to 80microns) diamond like carbon protective coating on internal as well as external surfaces of products ranging from automotive liners and piston rings to long production pipes used in the oil and gas industry. The company’s technology is protected by two granted and ten pending patents. This paper presents results of a development effort to combine hollow cathode plasma technology with a bi-polar assymetric DC pulse power supply to produce a single junction, amorphous silicon based photovoltaic cell. It will be demonstrated that greater depostion rates, film uniformities and high gas utilization can be achieved, resulting in an estimated cost per watt of $0.20 per fabricated cell with efficiencies of 8-10% for standard single junction PiN diode. A reduction in solar cell cost is achieved with innovative machine design based on a modular roll-to-roll system employing 12 inch wide dual steel foils. Results of a structural and electrical characterization are presented describing the relationship between process parameters and photo-activity. It is shown that the hollow cathode deposition process is unique and results in crystal properties of the deposited materials that could lead to thin film solar cells with improved efficiencies over existing devices.