Design concept of a hybrid photo-voltaic/thermal conversion cell for mid-infrared light energy harvester

© 2017 Optical Society of America. Harvesting the thermal loss energy emitted as electro-magnetic (EM) waves (at solar, micrometer and millimeter spectral wavelengths) over the broadest possible spectral range is a major target in the development of sustainable energy solutions. Solar cells and rectennas suffer unavoidable energy losses due to heat generation as well as due to the transparency window (λ > 1100 nm for Si), which is not utilized in photo-electrical conversion. A hybrid photovoltaic/thermoelectric conversion system is presented as an extension of a typical Si solar cell and demonstrates additional capability in harvesting energy over the entirety of the solar spectrum. Nano-textured silicon - black-Si - was used to reduce reflectivity of the cell surface and a Ge-Sn layer was added below to facilitate absorption over the IR wing of the solar spectrum. An up to 7% improvement to the voltage generated by photo-voltaic conversion was obtained via the thermal-to-electrical contribution