Metallization of silicon solar cells using ps- and ns-pulsed lasers

Abstract

Metallization plays a fundamental role in the fabrication of solar cells and it is then a key process for enhancing the efficiency of silicon solar cells in a cost effective way. In this work, Laser Induced Forward Transfer (LIFT) technique has been used to direct write the metallic contacts (fingers and busbars) onto c-Si cells. Commercial silver pastes, used in conventional screen-printing process, are deposited onto a glass substrate, placed over the cell, and transferred be means of focusing a laser pulse in the interface between the paste and the glass substrate. Standard ns-pulsed diode pumped solid state lasers and new generation ps-pulsed industrial lasers have been used as laser sources for LIFT. Fine parameterization of the process is needed. Single dots of paste have been transfer in a wide parametric window. Once the optima experimental conditions are determined, it is possible using both pulse time durations to transfer large material volumes per pulse (~102 pL) and define metallic lines with large aspect ratios.