Low-cost copper conductive grids for thin-film solar cells formed by screen printing and laser sintering

A process to screen print and laser sinter copper metal grids on CIGS photovoltaic (PV) modules is presented. Localized laser sintering using a high-speed galvanometer scanner is used to render printed lines conductive at beam speed in excess of 1 m/s. It is shown that the laser process does not reduce the shunt resistance of mini-modules printed with all-copper grids, indicating that no thermal damage occurs due to the laser process. Considering the significant cost saving introduced by using copper paste, replacing silver grids with copper is shown as an attractive proposition for reducing the cost-per-watt of thin-film PV.