Mitigating the contact resistance limitation of cavitated fine line Ag paste by Laser-Enhanced Contact Optimization

TL;DR

This study demonstrates that laser-enhanced contact optimization (LECO) can significantly improve the electrical performance of cavitated silver paste in silicon solar cells by optimizing firing temperature and enhancing contact quality.

Contribution

The paper introduces LECO as a novel method to recover contact performance in cavitated Ag paste, enabling fine-line metallization with improved electrical properties.

Findings

LECO increased fill factor from 76.8% to 80.2% at 720°C.

Optimal firing temperature for cavitated paste is around 750°C.

LECO improves current collection and localized conduction.

Abstract

Cavitation-assisted Ag paste is a promising route for fine-line, low-silver metallization in silicon solar cells because it improves paste dispersion, extends shelf life, and reduces Ag consumption, but matching the contact performance of commercial pastes remains a challenge. Here, cavitated paste was evaluated on PERC solar cells at peak firing temperatures of 720, 740, 750, and 762 C, with and without laser-enhanced contact optimization (LECO). The results show a clear firing window: 720 and 740 {\deg}C produced high series resistance and reduced fill factor, 750 C gave the best pre-LECO performance, and 762 C showed additional electrical limitations with only limited LECO benefit. LECO selectively recovered the under-activated states, increasing fill factor from 76.8 to 80.2% at 720 C and from 76.7 to 79.8% at 740 C. Electroluminescence and conductive AFM further indicated improved current collection and stronger localized conduction after LECO. These results show that cavitated paste performance is governed primarily by a shifted contact-formation window, and that firing optimization combined with LECO provides a practical route to retain the fine-line advantage while improving electrical performance.