Fabricating high aspect ratio front contacts for solar cells by string-printing

Abstract

We are developing a method for the fabrication of high aspect ratio and high throughput solar cell front contacts, called string-printing. For this, a thread coated with silver paste approaches a silicon substrate until contact is made and then is pulled away to form high aspect ratio, ideally triangular-shaped silver contacts. Here, we describe the fabrication method and show first results. So far, we have been able to fabricate structures with an aspect ratio of 1 whereas we noticed a strong dependence on the thread diameter and the paste viscosity. Furthermore, we also suspect a dependence on the withdrawal speed of the thread. Our approach is a highly scalable, low temperature process that can boost the performance of solar cell metallization for the terawatt future.