Remarkably improved photo-charging and dark-discharging current in a faradaic junction solar rechargeable device by regulating the morphology of a semiconductor

Two-electrode solar rechargeable devices can converse and store solar energy without external bias. However, the photo-charging and dark-discharging current of these devices is low and limits their practical applications. Here, the photo-charging and dark-discharging current of Si/poly(N-methylpyrrole) (PNMPy) photoanode increases 21 and 10 times by preparing nanostructured Si semiconductor, up to 5.09 and 2.06 mA cm⁻², respectively. Further studies suggest that the improved current comes from higher separation efficiency of photo-generated carriers and new electron transfer paths on the surface of nanostructured Si. Moreover, a solar rechargeable device of Si/PNMPy/H₂SO₄(aq)/WO₃/FTO was prepared, which indicated good cyclic stability. These results deepen our understanding on the current in solar rechargeable devices and offer guidance for the design of other high-performance devices.