Laser scribing of fluorine doped tin oxide for serial interconnection of CdS/CdTe solar cells

Abstract

In thin film PV-module production the scribing of transparent conducting oxides, like fluorine doped tin oxides thin films, is performed with serial interconnection of solar cells without the use of external wires. This scribing is usually carried out with infrared and ultraviolet lasers, while for the other films that complete the solar cell structure, the scribing is performed with visible laser light. Thus, the use of only one laser in all scribing steps in the monolithic interconnection process could reduce the manufacture cost of PV-CdTe modules. In this work the laser scribing process on fluorine doped tin oxides is investigated using a Nd:YAG pulsed laser of 532 nm of wavelength with pulse duration of 50 nanoseconds. The corresponding threshold fluence was measured and the mechanism of interaction of laser radiation with the semiconductor oxide was studied, as well as the temperature distribution along the film and the time when it reached its maximum value after applying the pulse of radiation on the SnO$_{2}$:F layer.