Nanocopper to replace nanosilver inks for solar cell applications

Copper and silver are excellent conductors that are being used in the ink formulations to print conductive patterns to collect charge generated in photovoltaic cells (PV), i.e. to conduct electricity. Nanosilver and nanocopper are added to the ink formulation that are later used to print contacts on the solar cells. The printed contacts must be sintered (converting loose particles into a solid uniform mass) by heat, light or chemically to achieve good conductivity. Nanosilver and nanocopper require lower sintering temperature to achieve good conductivity due to their small size and this makes them an attractive option to make contacts. Silver dominates the solar energy and printed electronics market, though there is a growing interest to switch to copper as a much more economic option – one gram of copper costs circa 0.09 USD vs 0.71 USD for silver. The key challenge with copper is that it oxidises, and copper oxide is non-conductive. This is a major drawback but also an opportunity. Pro for nano is designing a new production reactor which will operate under vacuum, so there is an opportunity to produce high quality copper nanomaterials for ink formulations and to avoid (or minimise) oxidation.