Flexible thin films on textiles for solar cells

Abstract

In recent years, there has been an increase in studies about developing photovoltaic fabrics which can be used in different textile and clothing applications. The flexibility of the solar cells could be useful in many applications, for example providing power for small portable electronic devices such as personal digital assistants or on a larger scale for sunshades and canopies. In this work, we have taken the direct approach to deposit amorphous silicon cells directly onto fabrics. To achieve that, we have studied approaches to obtaining flexible conductive surfaces on polyester fabrics by using a double layer of metal and commercially available conductive polymer. Then both single and stacked metal contact layers and thin amorphous silicon films were built on glass and flexible substrates for optical and electric characterisation. It was shown by bending tests that the conductive fabrics retain both flexibility and electrical conductivity. Finally, complete n-i-p single junction a-Si:H cells were fabricated on different types of substrates such as glasses, polyester fabric and polytetrafluoroethylene fabric (PTFE). Several challenging aspects related to the fabrication and characterisation of solar cells on fabrics are highlighted. Cells on woven fabrics were shown to be active photovoltaic devices though with lower response than equivalent cells on rigid glass substrates.