Nanobelt-carbon nanotube cross-junction solar cells

Nanostructures such as carbon nanotubes (CNTs) and semiconducting nanowires are promising candidates for developing next-generation photovoltaics. Here, we report solar cells using individual single-walled or double-walled CNTs and CdSe nanobelts arranged in simple cross-junction configurations. The CNT and CdSe nanobelts form reliable line contacts at their intersections, resulting in efficient heterojunction solar cells with power conversion efficiencies up to 1.87% and stable performance in air over long periods. Both semiconducting and metallic CNTs can form solar cells with CdSe nanobelts, with similar open-circuit voltages but different short-circuit current densities. We can integrate multiple CNTs in parallel with a single nanobelt to construct an array of cross-junction solar cells simultaneously, with scaled current output, indicating the possibility of parallel device connection and large-scale production. Our results show the potential of utilizing one-dimensional nanostructures to design and fabricate high performance photovoltaic devices with well-defined and scalable structures.