Neutralization of the impact of belt speed on screen printed copper metallization by LECO on PERC homogeneous emitter

TL;DR

This study demonstrates that LECO treatment neutralizes the effects of belt speed variations during copper metallization firing, resulting in consistent electrical performance and high efficiency in PERC solar cells.

Contribution

The paper introduces a LECO treatment process that mitigates belt speed effects in copper metallization, ensuring uniform electrical properties in PERC solar cells.

Findings

LECO treatment equalizes electrical parameters across different belt speeds.

Series resistance decreases significantly after LECO treatment.

Achieved solar cell efficiency of 20.8% on homogeneous PERC emitter.

Abstract

Copper fire-through metallization is a cost-effective alternative to Ag counterpart for industrial high efficiency solar cells. The fire through dielectric metallization relies on belt speed, which dictates the ramp up and ramp down rates for effective contact formation. In this paper three belt speeds (325oC, 360oC, 390oC) at constant peak firing temperature, were used to process PERC (homogeneous emitter) cells. After the contact firing the electrical parameters were dependent on belt speed, but after LECO treatment, they were identical. The SEM/EDS cross sectional analyses showed increased elemental Cu with belt speed, and the series resistance was lowest for the middle belt speed before LECO. However, after the LECO treatment, the series resistance dropped, respectively, to 0.503 ohm-cm-2, 0.428 ohm-cm-2 and 0.500 ohm-cm-2 leading to efficiency of 20.8% on homogeneous PERC emitter.