An Equivalent Circuit for Perovskite Solar Cell Bridging Sensitized to Thin Film Architectures

Abstract

Fundamental working mechanisms of perovskite solar cells (PSCs) remain an elusive topic of research. Impedance spectroscopy (IS) has been key to characterizing photovoltaic devices; however, its application to PSCs has generated misleading outputs. In this work, we control the precursor concentrations to fabricate a series of PSCs with different amounts of perovskite absorber. While lower concentration devices present the well-known dye-sensitized impedance pattern, the characteristic impedance spectrum of thin-film PSCs arises for higher concentrations. The capacitances’ evolution is employed to identify the dominant physical processes in the spectrum and reveals that it is not possible to assign a single physical origin to each individual feature. On the contrary, their resistances present contributions from different physical processes, including charge transport and recombination. We provide an equivalent circuit to evaluate the IS of PSCs in terms of the processes directly affecting their performance, a tool for further development of perovskite photovoltaics.