Analysis of electrochemical impedance spectroscopy of hybrid perovskite devices

D. Moia, J. Maier

Understanding the long-time scale behavior of hybrid perovskites is a key challenge to the development of reliable solar cells based on these materials. Different interpretations for such behavior, commonly characterized by low frequency features in the impedance spectra of devices, have been suggested.

Our approach aims to disentangle the complexity introduced by the mixed conducting nature of hybrid perovskites through a combination of experimental and numerical tools.

Fig. 1. Electrical characterization of hybrid perovskite devices. (a) DC polarization measurement and (b) impedance spectrum of a sample with MAPI contacted between gold contacts. The relevance of the low frequency behavior is evident in both measurements.

Fig. 1. Electrical characterization of hybrid perovskite devices. (a) DC polarization measurement and (b) impedance spectrum of a sample with MAPI contacted between gold contacts. The relevance of the low frequency behavior is evident in both measurements.

Investigation of the high frequency (short time scale) and low frequency (long time scale) electrical response allows to extract information on the electronic and ionic conductivities of hybrid perovskite devices (Fig. 1).

*Fig. 2. Simulations of impedance spectra based on the transmission line model.*

*Fig. 2. Simulations of impedance spectra based on the transmission line model.*

Simulations of impedance aid the interpretation of experimental results and show that the features in the low frequency range can be associated to electrode and stoichiometric polarization in the hybrid perovskite mixed conductor.