Evolution of performance parameters of perovskite solar cells with current-voltage scan frequency

TL;DR

This paper introduces a novel sinusoidal excitation method to analyze how current-voltage scan frequency affects the performance and hysteresis behavior of perovskite solar cells, revealing frequency-dependent internal processes.

Contribution

It develops a new analytical approach using large amplitude sinusoids to study frequency effects on perovskite solar cell performance, focusing on internal ion-controlled recombination mechanisms.

Findings

Performance parameters vary with scan frequency.

Hysteresis phenomena are linked to internal ion dynamics.

Impedance spectroscopy correlates with frequency-dependent behavior.

Abstract

Current-voltage measurements are a standard testing protocol to determine the efficiency of any solar cell. However, perovskite solar cells display significant kinetic phenomena that modify the performance at several time scales, due to hysteresis, internal capacitances, and related mechanisms. Here, we develop a method to analyze the current-voltage curves by using large amplitude sinusoids as the excitation waveforms, specifically addressed to determine the influence of cycling frequency on the performance parameters. We solve a system of equations representative of charge collection and recombination, that provide the frequency-dependent dynamical behavior of the internal ion-controlled surface recombination processes that cause open-circuit voltage variations often observed in high performance devices. We analyze several reported experimental data, and we feature the key parameters governing the evolution of hysteresis phenomena as the scan speed is increased in relation to Impedance Spectroscopy.