Implementation of nickel and copper as cost-effective alternative contacts in silicon solar cells

Efficient metal contact formation is pivotal for the production of cost-effective, high-performance crystalline silicon (Si) solar cells. Traditionally, screen-printed silver (Ag) contacts on the front surface have dominated the industry owing to their simplicity, high throughput, and significant electrical benefits. However, the high cost associated with using over 13–20 mg/Wp of Ag can impede the development of truly cost-effective solar cells. Therefore, there is an urgent need to explore alternative, economically viable metals compatible with silicon substrates. This study reports on the application of a contact stack consisting of Ag, nickel (Ni), and copper (Cu) in Si solar cells. To prevent Schottky contact formation, Ag is implemented as a seed layer, whereas Ni and Cu form the metal bulk layer. The fabricated bi-layer stack without selective emitter exhibits a maximum efficiency of ~21.5%, a fill factor of 81.5%, and an average contact resistance of 5.88 mΩ·cm² for a monofacial PERC cell. Microstructure analysis demonstrates that the metals within the contacts remain distinct, and Cu diffusion into the silicon during the firing process is absent. Consequently, printed bi-layer contacts emerge as a promising alternative to Ag contacts, reducing the Ag consumption to below 2.5 mg/Wp per cell without compromising overall efficiency.