Figure 5

Nyquist plots (scattered) and their fitting results (line) of QDSCs with various counter electrodes under bias of V _oc (under illumination of AM1.5). The inset (above) shows the detailed plots in the high-frequency region; (below) the equivalent circuit for the QDSC with the representation of impedance at CE/electrolyte interface (subscript CE), TiO₂/CdS/CdSe/electrolyte interface (subscript 1) and series resistance (subscript s, including resistance in TiO₂ film and electrolyte). The symbols R and CPE describe a resistance and a constant phase element, respectively; W accounts for finite-length Warburg diffusion