Proceedings of Online nanoGe Fall Meeting 20 (OnlineNFM20)
Publication date: 4th October 2020
The dynamic response of metal halide perovskite devices shows a variety of physical responses that need to be understood and classified for enhancing the performance and stability and for identifying new physical behaviours that may lead to developing new applications. These responses are the outcome of complex interactions of electronic and ionic carriers in the bulk and at interfaces. Based on a systematic application of frequency modulated techniques and time transient techniques to the analysis of kinetic phenomena, we present a picture of the dominant effects governing the kinetic behaviour of halide perovskite devices. First with impedance spectroscopy we provide an interpretation of capacitances as a function of frequency both in dark and under light, and we discuss the meaning of resistances and how they are primarily related to the operation of contacts in many cases. Working in samples with lateral contacts, we can identify the effect of ionic drift on changes of photoluminescence, by the creation of recombination centers in defects of the structure. We also address new methods of characterization of the optical response by means of light modulated spectroscopy. The IMPS is able to provide important influence on the measured photocurrent. We apply the dynamic picture to the characterization of perovskite memristors. A memristor is a device that has different metastable states at a voltage V. It has a resistance that depends on the history of the system, and the states can be switched by applied voltage. It is simpler than a transistor in that the control occurs by 2 contacts. As a summary we suggest an interpretation of the effects of charge accumulation, transport, and recombination, how these effects influence the current-voltage characteristics and time transient properties, and we suggest a classification of the time scales for ionic/electronic phenomena in the perovskite solar cells.