Predictive Modeling for Glass Side Laser Scribing of Thin Film Photovoltaic Cells

Abstract

Laser scribing of multilayerthinfilm solar cells is an important process for producing integrated serial interconnection of minimodules, used to reduce photocurrent and resistance losses in a largearea solar cell. Quality of such scribing contributes to the overall quality and efficiency of the solar cell, and therefore predictive capabilities of the process are essential. Limited numerical work has been performed in predicting the thin film laser removal processes. In this study, a fullycoupled multilayer thermal and mechanical finite element model is developed to analyze the laserinduced spatiotemporal temperature and thermal stress responsible for SnO2:F film removal. A plasma expansion induced pressure model is also investigated to simulate the nonthermal film removal of CdTe due to the microexplosion process. Corresponding experiments of SnO2:F films on glass substrates by 1064 nm ns laser irradiation show a similar removal process to that predicted in the simulation. Differences between the model and experimental results are discussed and future model refinements are proposed. Both simulation and experimental results from glassside laser scribing show clean film removal with minimum thermal effects indicating minimal changes to material electrical properties.