Upscaling thin film solar cells for water treatment devices

Abstract

The availability of clean drinking water and various energy sources has always been taken for granted and considered to be infinite throughout human history. However, nowadays, we have reached a historical moment in which we are over-exploiting the Earth's resources. The reduction of the high level of pollution in the air and in the water is one of the main challenges that the next generations will have to face. Photovoltaic technologies offer a clean and cheap solution for both water purification and hydrogen generation for energy storage.

The main goal of this thesis is to upscale lab-scale thin film solar cells, by a factor of 600, optimized for water treatment devices. To this end, two alternative solutions have been explored.

On the one hand, a metallic front contact grid has been designed to minimize the power losses in large area pin superstrate solar cells. On the other hand, a thin film mini-module has been manufactured by isolating small area nip substrate solar cells and connecting them in parallel.

The implementation of the front metallic grid has enabled the upscaling of pin superstrate amorphous silicon solar cells by a factor of around 10. Additionally, the laser ablation process needed for dividing the sample into multiple cells has been studied and optimized for nip substrate amorphous silicon devices. Finally, some of the major problems that cause the formation of shunts have been identified. However, the relatively high density of shunts through the amorphous silicon bulk prevents the device from achieving higher efficiencies at larger dimensions.