Abstract
Invisible power generation by natural and artificial light enables sustainability by onsite-power deployment, lower cost, and minimal burden on the built environment. However, dark, opaque photovoltaics limit light utilization in a transparent way. Herein, it is proposed that the active energy window (AEW) invisibly features power production, providing higher freedom for onsite power generators in window objects without limiting human vision. The AEW has a transparent photovoltaic (TPV) for onsite power and a transparent heater (TH) to remove the effects of shadows from snow and recover the power lost. Moreover, a heating function is applied to remove the effects of weathering related to snow. The proposed prototype integrates a TPV-TH, offering ultraviolet (UV)-blocking, daylighting, thermal comfort, and onsite power with a power conversion efficiency of 3% (AM1.5G). Field-induced transparent electrodes are applied to the TPV-TH and designed considering the AEW. Owing to these electrodes, the AEW ensure a wide field-of-view without optical dead zones, ensuring see-through vision. The first TPV-TH integration is performed into a 2 cm2 -window that generates onsite power of 6 mW and has an average visible transmittance of ≈39%. It is believed that light can be utilized with comfort through the AEW in self-sustainable buildings and vehicles.