1,8-Octanedithiol as an Effective Intermediate Layer for Deposition of Cu Electrodes via Inkjet Printing and Laser Sintering on III-V Triple-Junction Solar Cells

This research study combines surface modification techniques with back-end-of-line (BEOL) methods for cost-effective, scalable front contact electrode deposition on III?V solar cells. Copper nanoparticle grids are deposited by inkjet printing on surface-modified III?V solar cells. The deposition of a self-assembled monolayer (such as 1,8-octanedithiol) as an intermediate layer is a proven method for surface modification to improve the wettability of the substrate surface and the adhesion of the printed copper nanoparticle structures on the substrate to perform inkjet printing of coherent and narrow electrode structures. Then, the printed copper ink is converted to a conductive copper grid by a picosecond pulsed laser with optimized settings and an additional galvanic plating step is required for the thickening of inkjet-printed and laser-sintered seeding layer for solar cell applications. As a result, an ohmic copper contact on III?V layer with low contact resistivity (5?mΩ?cm2) is realized successfully. The processed solar cell shows a functioning behavior with 20% conversion efficiency.