Interpretation of Resistance, Capacitance, Defect Density and Activation Energy Levels in Single-Crystalline MAPbI3
A. Kalam, R. Runjhun, A. Mahapatra, M. M. Tavakoli, S. Trivedi, H. T. Dastjerdi, P. Kumar, J. Lewiński, M. Pandey, D. Prochowicz, P. Yadav
Journal of Physical Chemistry C, 2020, 124, 3496-3502
Hybrid inorganic−organic lead halide perovskites have attracted a significantresearch interest in the last 10 years due to their broad-area applications in optoelectronicdevices such as solar cells, lasers, photodetectors, and light-emitting diodes (LEDs).Fundamental understanding of the charge transportation, defect density, and activation energyis very important for the further progress of this class of semiconductors. Here, we shed light onthe interpretation of resistance, capacitance, defect density, and activation energy levels insingle-crystalline methylammonium lead iodide (MAPbI3). In particular, the impedanceresponse of the MAPbI3 crystal as a function of applied bias and temperature (under bothincreasing and decreasing temperature cycles) is studied for thefirst time. From the detailedbias- and temperature-dependent studies, we found that the low-frequency capacitance valuesare influenced by ion density and mobility. Consequently, single-crystalline MAPbI3 depicts anactivation energy of 0.53−0.54 eV with an exceptionally low electronic trap density of 0.96×1010cm−3. The present study illustrates that the net electrochemical impedance spectra are due to ionic capacitance coupled to aresistance. The associated resistance is related to the conductivity of the perovskite crystal. Thesefindings are helpful to understandthe fundamental electrical properties of the MAPbI3 single crystal, which could be useful for the further advancement of perovskitesingle-crystal-based applications.