Abstract
AbstractBeing based on mixed ionic‐electronic semiconductors, the operation of perovskite solar cells depends on many parameters. To develop an experimentally validated numerical device model, it is therefore necessary to isolate individual physical phenomena. To this end, the dynamics of ion motion in lead halide perovskites is investigated by measuring impedance spectra and the electric displacement as a function of frequency in dark. The displacement response is fully reproduced by a numerical device model that combines electronic and ionic conduction. For a quantitative description of the displacement, it is critical to consider the frequency‐dependent apparent dielectric constant, the ion concentration and the ion diffusion coefficient. The numerical simulations enable to quantify the effect of ion motion and voltage scan speed on the electric field distribution in MAPbI3 based devices, laying the foundations for an experimentally validated perovskite device model.
Highlights
Being based on mixed ionic-electronic semiconductors, the operation of perovskite solar cells depends on many parameters
The dynamics of ion motion in lead halide perovskites is investigated by measuring impedance spectra and sion was predicted to be the fastest diffusion, where positively charged I− vacancies are the mobile species instead of I− ions.[7]
The hysteresis in the J–V characteristics are in accordance with such slow moving speed on the electric field distribution in MAPbI3 based devices, laying the foundations for an experimentally validated perovskite device model
Summary
To obtain the ion concentration, ion-diffusion coefficient, and frequency-dependent apparent dielectric constant, we first use impedance spectroscopy. With a sample thickness L = 240 nm, an ion diffusion coefficient Dion of 1 × 10−15 m2 s−1 is obtained via Equation (7)
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