Implementation of Nickel and Copper as Cost-Effective Alternative
Contacts in Silicon Solar Cells
Abstract
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 13-20mg/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,
while 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 5.88mΩ·cm 2 for a monofacial PERC cell.
Microstructure analysis demonstrate 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 2.5mg/Wp per cell without compromising overall efficiency.