Interconnect Manufacturing Process for Thin Film Solar Cells (IMP)

Thin film photovoltaics differ from the more common crystalline silicon solar panels which are made up of individual cells, connected in series and laminated to a glass panel. Thin film modules comprise um-scale layers of transparent electrode, semiconductor (containing a PN junction to form a photodiode) and metal back contact directly deposited on a glass panel. The semiconductors are typically silicon, cadmium telluride or CIGS. Organic semiconductors for thin film PV are a very active research field.
Thin film PV has many advantages over crystalline silicon PV including reduced materials costs and monolithic series interconnection (needed to generate appropriate voltage and current) during the manufacturing process. Series interconnection of thin-film modules is usually achieved by alternating vacuum deposition of layers with ambient laser scribing processes. This requires breaking vacuum between each of the deposition steps. The ability to deposit the entire stack without breaking vacuum would reduce process and factory complexity, reduce tool costs and give better process control, improving performance.
The “One Step Interconnect” (OSI) being developed here interconnects the module, post deposition, using a patented combination of laser and inkjet processes. This drives down the cost per Watt of PV electricity, sustaining PV adoption and reduction of CO2 emissions.