Use of Single Wall Carbon Nanotube films doped with Triethyloxonium Hexachlorantimonate as a Transparent Back Contact for CdTe Solar Cells

Highly conductive transparent films were formed by doping single-wall carbon nanotubes (SWCNTs) networks with triethyloxonium hexachlorantimonate (OA). This doping can result in complete quenching of the SWCNT absorption features in the visible and infra-red (IR) range leaving an IR transparent film. These doped SWCNT films were investigated for possible use as a transparent back contact for CdTe-based devices. One particular goal is the development of tunnel junction for use in tandem cells. The transmittance of device stacks with and without an OA-doped SWCNT back contact was nearly identical. However, it was found that during the doping process, the OA interacted more strongly with the CdTe layer than the SWCNTs, resulting in reduced device performance. The average power conversion efficiency decreased from 11.8% for a standard Cu/Au back contacted device to 10.6% for the OA-doped SWCNT back contacted device.