Spin‐On SiO x ‐Assisted Inkjet Printing for Interdigitated n+ and p+ Poly‐Si/SiO x Contacts in Silicon Solar Cells With Suppressed Unintended Doping

The fabrication of localized doped polycrystalline silicon (poly‐Si) passivating contacts, such as in an interdigitated back contact (IBC) solar cell, is complex and costly. Inkjet printing offers a promising route to simplify this process; however, unintended doping and cross‐doping from the liquid dopant sources remain a significant challenge. This study demonstrates the effectiveness of a spin‐on SiO x capping layer in suppressing unintended doping in unprinted regions and cross‐doping between dopant species, enabling the simultaneous formation of localized n+ and p+ poly‐Si passivating contacts using inkjet printing via a single high‐temperature annealing step. Secondary ion mass spectrometry (SIMS) mapping reveals uniform doping concentrations within the printed lines, approximately 1 × 10 20 cm −3 for phosphorus and 2 × 10 20 cm −3 for boron in the poly‐Si layers with minimal lateral diffusion at the line edges. More importantly, unintended doping is now reduced to below 9 × 10 17 cm −3 , just 0.5% of the source doping concentrations. Additionally, cross‐doping in the printed region of opposite polarity remains below 5 × 10 18 cm −3 , which is less than 2.6% of the intended doping. These results pave the way for the potential adoption of inkjet printing in simplifying the fabrication of solar cells and other electronic devices.