Backcontact CdSe/CdTe windowless solar cells

This paper details the fabrication and properties of CdSe/CdTe thin film photovoltaic devices with a dual back contact geometry. Device fabrication involves CdSe electrodeposition on one of two interdigitated electrodes on a pre-patterned substrate followed by CdTe electrodeposition over the entire structure so that both electrodes are behind the active portion of the device. In contrast to traditional planar devices, illumination is on the electrode-free CdTe surface rather than through a window layer. Like previously detailed back-contact devices for other materials systems, all light that impinges on the device thus reaches the CdTe absorber, the surface being free of metallic electrodes, transparent conductors and window layers. Device efficiency of 2% under simulated air mass 1.5 illumination for feature spacing of 2 μm is similar to that of three-dimensionally patterned CdS/CdTe devices detailed by other groups with similar feature height but much smaller 0.5 μm spacing.