Understanding the Full Zoo of Perovskite Solar Cell Impedance Spectra with the Standard Drift‐Diffusion Model

Understanding the Full Zoo of Perovskite Solar Cell Impedance Spectra with the Standard Drift-Diffusion Model

Impedance spectra of perovskite solar cells are varied and complex, often exhibiting multiple features and apparent negative capacitance. While these unusual spectra are often attributed to non-ideal measurement conditions or device degradation, it is shown that they are in fact a natural consequence of a mixed ionic-electronic conduction model in certain conditions and connect each to specific bottlenecks in device efficiency.


Abstract

The impedance spectra of perovskite solar cells frequently exhibit multiple features that are typically modelled by complex equivalent circuits. This approach can lead to the inclusion of circuit elements without a sensible physical interpretation and create confusion where different circuits are adopted to describe similar cells. Spectra showing two distinct features have already been well explained by a drift-diffusion model incorporating a single mobile ionic species but spectra with three features have yet to receive the same treatment and have even been dismissed as anomalous. This omission is rectified here by showing that a third (mid-frequency) impedance feature is a natural consequence of the drift-diffusion model in certain scenarios. Our comprehensive framework explains the shapes of all previously published spectra, which are classified into six generic types, each named for an animal resembling the Nyquist plot, and approximate solutions to the drift-diffusion equations are obtained in order to illustrate the specific conditions required for each of these types of spectra to be observed. Importantly, it is shown that the shape of each Nyquist plot can be linked to specific processes occurring within a cell, allowing useful information to be extracted by a visual examination of the impedance spectra.

Understanding the Full Zoo of Perovskite Solar Cell Impedance Spectra with the Standard Drift-Diffusion Model

Impedance spectra of perovskite solar cells are varied and complex, often exhibiting multiple features and apparent negative capacitance. While these unusual spectra are often attributed to non-ideal measurement conditions or device degradation, it is shown that they are in fact a natural consequence of a mixed ionic-electronic conduction model in certain conditions and connect each to specific bottlenecks in device efficiency.

Abstract

The impedance spectra of perovskite solar cells frequently exhibit multiple features that are typically modelled by complex equivalent circuits. This approach can lead to the inclusion of circuit elements without a sensible physical interpretation and create confusion where different circuits are adopted to describe similar cells. Spectra showing two distinct features have already been well explained by a drift-diffusion model incorporating a single mobile ionic species but spectra with three features have yet to receive the same treatment and have even been dismissed as anomalous. This omission is rectified here by showing that a third (mid-frequency) impedance feature is a natural consequence of the drift-diffusion model in certain scenarios. Our comprehensive framework explains the shapes of all previously published spectra, which are classified into six generic types, each named for an animal resembling the Nyquist plot, and approximate solutions to the drift-diffusion equations are obtained in order to illustrate the specific conditions required for each of these types of spectra to be observed. Importantly, it is shown that the shape of each Nyquist plot can be linked to specific processes occurring within a cell, allowing useful information to be extracted by a visual examination of the impedance spectra.

Leave a Replay

About Us

Energy One is a leading manufacturer of EV charging equipment and installation services. We are an industry-leading EV charger manufacturer with software, equipment installation, and support.

Recent Posts

Leave this field blank

Sign Up for Our Newsletter

Get all latest charging, regulatory, incentive, technology and renewable news

Sign up for our newsletter.  Get the latest news in renewables, EV’s , battery technology, the latest trends and EV Charging.

Keep up with all the news from EnergyOne

Sign up for our EV Charging and Renewables Newsletter. Get the latest news on everything EVSE:  The latest technology to rebates.  (one email or less per week).

Leave this field blank

Get charging today!

Plan, Engage, Launch!

Talk to our team about your project

Fill out the form below and we will get back to you within the next 24 hours.

Leave this field blank