Formation of a copper contact grid on the surface of silicon heterojunction solar cells

Abstract

A comparative analysis of various methods of forming a copper (Cu) contact grid on the surface of silicon heterojunction solar cells (SHJ SC) as an alternative to the standard screen printing method using expensive silver-containing (Ag) pastes is presented. It has been shown that the use of inkjet printing for the formation of protective dielectric masks based on an organic polymer and thin buffer metal layers for the growth of a Cu contact grid by electroplating makes it possible to form a contact grid of the required shape and having sufficient adhesion to the surface of SHJ SC. Using this method, double-sided SHJ SC (size 157x157 mm2) with Cu contact mesh were fabricated, demonstrating an efficiency of 22.9% and an adhesion level of 3-5 N/mm compared to 22.6% and 1.5-2 N/mm using a similar contact mesh based on Ag paste. Keywords: solar energy, monocrystalline silicon, heterojunction solar cell, copper contact grid, electroplating, screen and inkjet printing.