Study of CIGS photovoltaic processing with femtosecond laser pulses at IR wavelength

The aim of this study is to report the femtosecond laser with the characteristics of ultra-short pulse to develop the laser scribing technique of CIGS thin-film solar cells. In recent years, the P1 layer has always been scribed by long-pulse laser. The P2 and P3 layers are usually scribed by using high precision machine. To make a breakthrough in scribing processes for CIGS solar cell, the femtosecond laser scribing technique is proposed in this work. The wavelengths of femtosecond laser scribing in our work are in the range of infrared. The P1, P2 and P3 layers are scribed by using femtosecond laser processing at 1035 nm. In order to investigate the film, samples were scribed with the laser beam, and subsequently measured for film composition by X-ray fluorescence (EDS-XRF) spectroscopy. Optical microscopy was used to characterize the appearance of the scribed lines. A scanning electron microscope (SEM) and optical microscope (OM) were utilized to inspect the appearance of the laser treated films. The experimental results indicated that the substrates made of Mo (Molybdenum), CIGS and ZnO (ITO) can all be employed and the edges of metal device are especially suitable for femtosecond laser scribing. The scribing speed of femtosecond laser for Mo/glass substrate can reach as high as 2000 mm/s. Through the study, we got the best processes parameters of manufacturing. The results of this study indicated femtosecond laser can indeed improve the scribing quality in processing Mo material and CIGS thin-film as well.