Copper based front side metalization contacts screen printed and fired in air demonstrating durability

Abstract

The front side metallization of silicon solar cells is almost exclusively silver that is deposited using a screen-printed process followed by a sintering step at high temperatures. Over the past decade the industry has severely reduced the amount of silver required, but the material still accounts for about 8 percent of the cost of a solar panel. Copper is a fraction of the cost, but requires multiple layers to protect the underlying silicon wafer and thus is not readily integrated into existing manufacturing plants. In this paper, a copper-based paste is screen printed onto a SiN coated silicon wafer and passed through a high temperature furnace in air. The performance of the device is measured using typical characterization tools. Accelerated testing of the device at elevated temperatures demonstrates an operational device with very little degradation after 1,000 hours at elevated temperature.