Highly Transparent, Scalable and Stable Perovskite Photovoltaics without Compromising Aesthetics

Transparent photovoltaics (TPV) are rapidly emerging as a promising solution to electrify glass surfaces of buildings and vehicles to provide point-of-use power without impacting aesthetics. Though TPV development has mostly focused on the photon-rich, near-infrared portion of the solar spectrum, TPVs harvesting ultraviolet (UV) photons have significantly higher transparency and color neutrality, and can potentially provide trickle power for low-power electronics that prioritize aesthetics. However, none of today’s TPVs has demonstrated compatibility with the full-slate of stringent requirements for practical TPV applications—namely aesthetic performance, long-term operational stability, scalability, while providing sufficient power for such applications. Here, we demonstrate the first UV-absorbing TPV that satisfies these criteria by using CsPbCl_2.5Br_0.5 as the UV–absorber. By precisely tuning the halide ratio during thermal co-evaporation, we access high-quality large-area perovskite films with the ideal absorption cutoff for optimal aesthetics. The resulting functional TPV exhibits a record-high average visible transmittance of 84.6% and a near-perfect color rendering index of 96.5, both of which are comparable to that of common clear window glass and exceed that of any solar cell reported to-date. In addition, these TPVs demonstrate a power-conversion efficiency of 1.1%, more than twice that of the current record for UV-harvesting TPVs. Further, these TPVs show high operational stability with extrapolated lifetimes of >20 years under outdoor conditions. The functioning device prototype can be made as large as 25 cm², representing the largest transparent solar cells reported to-date.