Photovoltaic windows based on ultrathin transition-metal dichalcogenides: Natural indoor illumination spectra and energy-saving potential

Semitransparent photovoltaic windows are attractive for building-integrated applications because they can regulate natural indoor illumination while generating power. In this work, we assess the potential of transition metal dichalcogenide (TMDC) semitransparent solar cells as emerging technology for this application. We model a semitransparent ultrathin photovoltaic device containing a MoS 2 or WSe 2 absorber and find that it can be optimized to produce a balanced absorption of the sunlight spectrum because of the unique optical properties of these materials, eliminating the common problem of the undesired coloring of the transmitted light. The device also exhibits high angular absorptance. We estimate a potential saving between 16 % (winter) and 23 % (summer) in the electricity consumption of a high-rise office building located in Madrid, Spain, by implementing TMDCs semitransparent windows with an average photopic transmission (APT) of 24 %. Notably, this is compatible with a high quality in the transmitted light: the color rendering index (CRI) of the PV windows exceeds 90 for an APT between 23 % and 65 %. These results, along with the fact that TMDCs can be deposited using low-cost, scalable methods, indicate that TMDCs hold great potential for developing color-neutral, power-generating building glazing. • The optical properties of TMDCs make them excellent candidates for color-neutral power-generating windows. • We analyze ultrathin devices with absorber thickness between 3 and 55 nm. • High spectral quality of the transmitted light with CRI > 90 for any average photopic transmission down to 23 %. • An estimation of electric power generation for a case-study high-rise building is provided.