Analysis of different printing technologies for metallization of crystalline silicon solar cells

Crystalline silicon solar cells have been the workhorse of the Solar Photovoltaic industry, contributing to >90% of the total installations. The fabrication of solar cells involves multi-process steps i.e. chemical treatment, diffusion, passivation and metallization. Among these process steps of solar cell manufacturing, metallization is the most critical one since it not only influences cell performance but also the cost of manufacturing to a great extent. A proper metallization process essentially helps in reduction of various electrical and optical losses. A lot of research is being carried out on various metallization technologies to arrive at an efficient, cost-effective solution for contact formation. Screen printing, flexographic printing, laser metal sintering and recently developed 3D printing are some of the technologies of interest in this field. While 3D printing, laser metal sintering, etc. are still at lab level, flexographic and gravure printing are in search of a suitable paste which can make the technology production-worthy. It is the screen-printed technology of solar cells that currently dominates the commercial market because of its low production cost and process simplicity. Amongst the several technologies that have been developed till date for cell metallization, the screen-printing technology promises to be the most reliable, rugged and production-worthy technology. In this paper, different metallization technologies viz. screen printing (conventional, knotless), stencil printing, light induced plating, metal sintering, flexographic printing, aerosol printing etc. used for contact formation in high efficiency silicon solar cells have been reviewed.