Figure 1. Schematic illustration of the PEC/DSSC tandem device.

For the left part, the back side of the photoanode is a hybrid cDBR consisting of an alternating dense and porous ITO layers on top of TiO₂/SiO₂ stack. The hybrid cDBR reflects short-wavelength light <500 nm (represented by the blue arrow) while transmitting longer-wavelength light (represented by the red arrow). Pt island is coated on its top. For the right part, dye/TiO₂ photoanode and Pt layer are placed at the two opposite sides.