Novel photoelectrochromic devices incorporating carbon-based perovskite solar cells

In the present work, we propose for the first time, the use of a carbon-based perovskite solar cell (PSC) in a “partly covered” photoelectrochromic (PEC) device, with a three-electrode architecture that de-couples the photovoltaic (PV) and electrochromic (EC) operation, thus enabling better control of the device optical modulation. The proposed configuration also permits solar power production when the EC window remains idle at a given coloration state. The PSC unit of the devices consists of an FTO/ZnO nanowire/ZrO2/Carbon stack infiltrated with the MAPbI3 perovskite and covering a mere 4% of the device area. The remaining 86% consists of a redox type electrochromic in the form of an FTO/WO3/Liquid Iodine redox electrolyte/Pt/FTO sandwich. The two units, PV and EC, share a common anode and have different cathodes. The fabricated devices with dimensions of 3.0 cm × 4.0 cm, exhibit initial visible transmittance around 50%, fast and reversible transmittance modulation (9:1 within 2 min), charge storage of 20 mC/cm2, with the PSC having a power conversion efficiency of nearly 3%. They can withstand more than 40 continuous coloration-bleaching cycles. With combination of optical and electrical measurements, some unique features of these devices have been revealed.