Contact shadowing losses reduction by fine line screen printing

Aim of this work is to transfer high efficiency concepts to large-scale crystalline silicon solar cell production, which is based on screen printing technology. The achievable cell efficiency obtainable by this technique is strongly affected by the limitation due to the contact shadowing losses necessary for reaching high Fill Factor values; indeed highest the FF, highest the surface coverage. An appealing way to overcome this limitation is to join screen printing to buried contact technology to get high aspect ratio grid pattern and, at the same time, a high FF value. Moreover this technology allows to easily define a selective emitter. Keeping to this purpose high resolution polymer screens or stencils with variable thickness have been tested. Both this steps have been obtained by adjusting the conventional screen printing process.