Towards a Universal Approach for the Analysis of Impedance Spectra of Perovskite Solar Cells: Equivalent Circuits and Empirical Analysis

Abstract

Impedance spectroscopy is a powerful electrochemical small‐perturbation technique that provides dynamic electrical data in solar cells. This technique has been widely used to characterize dye‐sensitized solar cells and perovskite solar cells (PSCs). Physical parameters are normally obtained by fitting to an equivalent circuit, composed of electrical elements which theoretically correspond to physical processes involved in the photoconversion process. A variety of equivalent circuits to model the impedance spectra of PSCs are commonly used by different research groups. In this work, we evaluate their performance and adequacy. We demonstrate the analytical and numerical equivalence of impedance expressions for Voight, matryoshka, and hybrid circuits, which are used to fit a typical impedance spectrum of a PSC and compare the resulting parameters to the empirical values obtained without any equivalent circuit. The numerical equivalence can be demonstrated by using two‐ and three‐component impedance spectra. In contrast, Maxwell‐type equivalent circuits reveal parameters that have a more complex relation to empirical values. The presence of inductive effects such as “loops” and “negative tails” in impedance spectra are also discussed in terms of negative values of resistances and capacitances. We propose a general protocol to analyze impedance data of PSCs and to extract useful information from them.

Understanding the Effect of Different Synthesis Conditions on the Physicochemical Properties of Mixed‐Ion Perovskite Solar Cells

“…To obtain more detailed information on charge transport in the investigated cells, we performed electrochemical impedance spectroscopy (EIS) measurements. The electrochemical response of perovskite solar cells contains the resonance response at two or three different frequencies, related to different timescales of the charge‐transfer processes . The Nyquist plots of the cells studied in this work (Figure S4 A, Supporting Information) exhibit two distinct time constants, so they are modelled by two resistor‐constant phase element (R‐CPE) circuits put in series with a resistance ( R S ).…”

Perovskite solar cells based on polyaniline derivatives as hole transport materials

“…The slope of this part of the curve is close to 45°, which suggests processes related to diffusion. The equivalent circuit analysis used here (figure 6) was based on previous findings that connect EIS to the properties of solar cells [32][33][34][35]. Apart from the series resistance (R s ) accounting for the ohmic contribution of contacts and wires, the first semicircle can be adjusted with a resistive element (R r ) and a capacitive element, represented by a constant phase element (CPE), both connected in parallel [33,36].…”

Elucidating the Impact of Charge Selective Contact in Halide Perovskite through Impedance Spectroscopy

“…The measurements based on MAPbI 3 and without Adv. [28][29][30] The values of R 1 used to model the IS are given in the Supporting Information and are in the range of 7-20 Ω. Interfaces 2019, 6,1901193 www.advmatinterfaces.de selective contact (Types A, B, and C) display a single semicircle, whereas the full device fabricated from MAPbI 3 (Type D) showed two semicircles at higher temperature (>330 K), attributed to the double relaxation behavior, one at the interface, while the other in bulk of perovskite.…”