Electronic Diffusion in Perovskite Solar Cells Obtained from Light-Modulated Frequency Techniques
Agustín Bou a, Juan Bisquert a
a Institute of Advanced Materials (INAM), Universitat Jaume I, 12006 Castelló, Spain
Proceedings of Device Physics Characterization and Interpretation in Perovskite and Organic Materials (DEPERO)
València, Spain, 2023 October 3rd - 5th
Organizers: Sandheep Ravishankar, Juan Bisquert and Evelyne Knapp
Invited Speaker, Agustín Bou, presentation 020
Publication date: 14th September 2023

Small perturbation techniques are commonly employed to extract device properties of solar cell devices. However, obtaining electronic parameters for diffusion and recombination through impedance spectroscopy in perovskite solar cells has proven elusive thus far, as the measured spectra do not exhibit electron diffusion. In a series of publications, we demonstrate that intensity modulated photocurrent and photovoltage spectroscopies (IMPS and IMVS) reveal a high-frequency spiraling feature that is governed by the diffusion-recombination constants, especially under conditions where carriers are generated far from the collecting contact.

Furthermore, we illustrate how these constants can obscure the diffusion trace in impedance spectra. We present two distinct models and experiments for different configurations: the standard sandwich-contacts solar cell device and the quasi-interdigitated back-contact (QIBC) device for lateral long-range diffusion. Our measurement results yield hole diffusion coefficients and lifetimes that align with previous findings in the literature. Notably, our analysis in the frequency domain effectively separates carrier diffusion (at high frequency) from ionic contact phenomena (at low frequency).

This discovery paves the way for a systematic determination of transport and recombination characteristics under various operando conditions.

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