Fig. 7From: Efficiency Enhancement of Solid-State CuInS2 Quantum Dot-Sensitized Solar Cells by Improving the Charge Recombinationa EIS spectra of the cell devices measured in the dark at − 0.4 V bias. The inset in a illustrates the equivalent circuit simulated to fit the impedance spectra. RS represents the substrate resistance. Rct and CPE represent the charge transfer resistance and capacitance at the HTM/counter electrode interface, respectively. Rr and Cμ represent the recombination resistance and chemical capacitance at the photoelectrode/HTM interface, respectively. b Cμ and c Rr at different applied voltages (Vapp), calculated from the fitting of the impedance spectraBack to article page