Avoiding Ionic Interference in Computing the Ideality Factor for Perovskite Solar Cells and an Analytical Theory of Their Impedance-Spectroscopy Response

Impedance spectroscopy (IS) is a straightforward experimental technique that commonly used to obtain information about the physical and chemical characteristics of photovoltaic devices. However, nonstandard behavior perovskite solar cells (PSCs), which are heavily influenced by motion mobile ion vacancies, has hindered efforts consistent theory PSC impedance. This work rectifies this omission deriving simple analytic model impedance response from underlying drift-diffusion charge-carrier dynamics ion-vacancy motion, via an intermediate shows extremely good agreement with in relevant parameter regimes. Excellent demonstrated between much more complex for applied biases (including both open circuit maximum power point at 0.1 1 Sun) close cell's built-in voltage ${V}_{\mathrm{bi}}$. Both models show qualitative IS data literature predict many observed anomalous features found measurements on PSCs. The provides practical useful tool interpret extract parameters experiments. We define parameter, ${n}_{\mathrm{el}}$ (the electronic ideality factor), particular significance physics, since, contrast apparent factor, value can be identify dominant source recombination cell independent its ionic properties.