The low-frequency impedance hook in perovskite solar cells (PSC) is a feature that has been frequently associated with the behavior of passive circuits of inductors or negative capacitances. However, if the experimental impedance data do not transform according to the Kramers-Kronig (KK) relations, the system does not fulfill the conditions of linearity, stability, causality and finiteness necessary for validating the impedance measurements and fitting it using passive circuit elements. In this study, we found that the impedance hook in a standard PSC configuration is not compliant with the KK transforms, and as such the system is active and unstable. We propose a model for this low-frequency behavior based on the active gyrator element which consists of two cross-coupled voltage-controlled current sources and has the capability of turning a capacitance into its dual inductive impedance.

钙钛矿型太阳能电池（PSC）中的低频阻抗钩是一个经常与电感器或负电容的无源电路的行为相关的功能。但是，如果实验阻抗数据未根据Kramers-Kronig（KK）关系进行变换，则系统将无法满足验证阻抗测量值并使用无源电路元件进行拟合所需的线性，稳定性，因果关系和有限性条件。在这项研究中，我们发现标准PSC配置中的阻抗挂钩与KK变换不兼容，因此系统处于活动状态且不稳定。