Characterization, modelling and optimization of industrial silicon thin film solar cells

Abstract

This PhD thesis has been mostly developed at T-Solar Global S.A., a factory of silicon thin film photovoltaic modules. The main objectives are divided in three lines of action. On the one hand, we have characterised the optical and electrical properties of silicon thin film layers and transparent conductive oxides, as well as 1cm2 research solar cells deposited in substrates of 2.6 m x 2.2 m size used in the T-Solar production line. To characterize the solar cells, we have mainly measured their current-voltage curves and spectral response. On the other hand, we have modelled the fabricated solar cell to save resources in the R & D experimental tests performed at the production line. Finally, we have developed a very fast spectral response equipment that allows to perform a measurement in about 1 s (against the 20 min needed by a classical spectral response equipment). Thus, we perform spatial mappings in a reasonable period of time to know how changes the short circuit current density along the modules and, hence, to understand how affects the layers non-uniformity in the efficiency. The final objective is to know the critical parameters which act in the process deposition of solar cells to optimize their efficiency and the continuously improvement in their quality. It is noteworthy that we have produced record solar cells with an efficiency of 9.56% in the initial state and 8.22% in the stabilized state, improving in about 12% the efficiency obtained at the beginning of this PhD thesis with this kind of research solar cells.