Study of lead-free perovskite photoconverting structures by impedance spectroscopy

In this paper, the impedance spectroscopy technique is applied to study the charge dynamics across the bulk and at the interfaces at elevated temperatures for a novel photoelectric element, consisting of the lead-free perovskite material. The results show that the device performance degrades at a temperature of 54 degrees C, but at a temperature of 35 degrees C traps are thermally activated in the perovskite layer. As a result, the charge transport resistance is dependent on the signal frequency and the interfacial capacitance associated with charge accumulation in-creases. At elevated temperatures, the high-frequency plots are related to the photon-induced charges, while at low frequencies the ions transfer and space charge accumulation affect the processes in the photoelectric element. Based on the measurements conducted, it is possible to propose an equivalent electric circuit that can be used to quantify important material parameters and to understand loss mechanisms for different solar cell ar-chitectures. New information was provided about the temperature limitations and critical thermal threshold where physical degradation of the lead-free perovskite occurred.