Product Code: ICAL06_M703

Laser Processing for Back-Contacted Silicon Solar Cells
Authors:
Peter Engelhart, ISFH; D-31860 Emmerthal Germany
Rainer Grischke, ISFH; Emmerthal Germany
Ruediger Meyer, ISFH; Emmerthal Germany
Aart Schoonderbeek, LZH; Hannover Germany
Andreas Ostendorf, LZH; Hannover Germany
Rolf Brendel, ISFH; Emmerthal Germany
Uwe Stute, LZH; Hannover Germany
Presented at ICALEO 2006

We present a high-efficiency back-contacted silicon solar cell concept, where laser technology is applied as a key processing tool. The main goal in PV research is to reduce the Watt-peak costs of solar cells significantly. Innovative cell concepts including robust and reasonable process technologies are necessary to provide highest efficiencies and low process complexity. Laser technology with its excellent features for material machining offers many opportunities to make economical manufacturing processes feasible for solar cell production. Since there is a tendency to thinner wafers, laser processing with its inherent feature of working in a non-contacting way is predestined. Moreover, it allows a high automation grade and thus a high throughput in the production line. We present experimental investigations of laser-induced damage in the silicon crystal and its impact on the electrical parameters of the solar cells. A variety of pulsed lasers, such as CO2 lasers, excimer lasers, Nd:YAG lasers and frequency-converted solid state lasers, are compared concerning their applicability of processing silicon solar cells. The impact of different laser parameters on the silicon damage is investigated by means of contactless carrier lifetime measurements. Finally, the electrical parameters of solar cells manufactured using different lasers will be presented and discussed.