Product Code: ICA10_M1304

High Precision Scribing of Solar Cell Films by a Picosecond Laser
Authors:
Wenqian Hu, Purdue University; W. Lafayette IN
Yung Shin, Purdue University; USA
Presented at ICALEO 2010

Efficiency of the thin-film solar cells with a large active area can be increased if small segments are connected in series in order to reduce recombination in thin films and related current loss. Thin film solar cells consist of basically three functional layers, i.e., Mo, CIS and ZnO. The paper presents the results of preliminary study on the laser machining characteristics of thin films used for solar cell panels by using picosecond laser scribing. The material used in the preliminary study is a CIGS film (thickness ~ 800nm) on Mo layer (thickness ~ 400nm) over glass substrates. The Mo layer is sputter deposited on the glass substrate. The CIGS nanoparticles ink was spin coated on the Mo layer followed by baking and rapid thermal annealing. The laser used in this study is a Nd:YVO4 picosecond laser with repetition rate up to 500KHz, pulse width 10ps, and wave lengths 532/1064 nm. Various operating parameters such as wavelength, repetition rate, scribing speed and average power, were varied to achieve good results With an optical scanner with such a high repetition rate, it was possible to perform scribing at a very high speed. The scribed slots measured by an optical profilometer and scanning electron microscopy are very uniform and free of thermal damage, thus clearing demonstrating the capabilities of high speed scribing by a pico-second laser.