Flexible CuS nanotubes–ITO film Schottky junction solar cells with enhanced light harvesting by using an Ag mirror

Here we report the fabrication of a novel photovoltaic device based on CuS nanotubes (CuSNTs) and indium tin oxide (ITO) Schottky junctions. Large-quantity synthesis of CuSNTs was accomplished via a solution-based sacrificial template method under moderate conditions, while ITO Schottky contacts were fabricated via micro-fabrication and pulsed laser deposition (PLD). Upon light illumination, CuSNTs?ITO Schottky junctions exhibited pronounced photovoltaic behavior, giving rise to a power conversion efficiency of 1.17% on a conventional SiO2/Si substrate. Furthermore, by utilizing PET as the substrate, transparent and flexible CuSNTs?ITO solar cells were constructed and showed performance close to their device counterparts on a rigid substrate. Notably, it was found that the flexible devices were robust against tensile strain and could stand a bending angle up to ?95?. To enhance the light absorption of the devices, an Ag mirror layer was deposited on the rear side of the PET substrate so as to allow multiple reflection and absorption of the incident light. As a result, the flexible devices showed a substantial performance improvement, yielding an efficiency of ?2%. Our results demonstrate that low-cost and environmentally friendly CuSNTs?ITO solar cells are promising candidates for new-generation photovoltaic devices.