Radial Junctions on Laser-Cutting Tinplate Enable Semitransparent Thin-Film BIPVs with Low Reflection and Designable Transmission

Semitransparent thin-film solar cells, especially those fabricated directly on building materials, have attracted much interest in the continuously increasing demands of building-integrated photovoltaic (BIPV) applications. Herein, radial junction (RJ)-structured hydrogenated amorphous silicon (a-Si:H) thin-film solar cells, directly constructed upon silicon nanowires (SiNWs) grown by a vapor–liquid–solid (VLS) process on the rough surface of the tinplate substrates, have been successfully demonstrated. After optimizing the SiNW density, an efficiency of 5.89% can be achieved, with an average value of 5.38 ± 0.39%. Compared to the conventional thin-film photovoltaics on glass substrates, the semitransparent RJ-structured thin-film solar cells on the laser-cutting tinplate substrates have a lower reflectivity, an adjustable/designable light transmission, as well as excellent mechanical stability. More importantly, tinplate and other steel/metal substrates can be used as construction materials; thus, the overall costs, including fabrication and installation costs as well as the building construction cost, can be largely reduced. These results highlight the promising potential of the RJ thin film technology on laser-cutting steel/metal substrates to fabricate low-cost, low-reflection, and mechanically stable semitransparent thin-film BIPV devices.