Inhaltspezifische Aktionen

Juli

Bild des Monats Juli 2016

J-V hysteresis in organic-inorganic perovskite thin films

Methyl ammonium lead iodide CH3NH3PbI3 and related materials are interesting absorber materials for a new generation of photovoltaic cells.
In a recent study (M. Stumpp, R. Rueß, J. Horn, J. Tinz, C. Richter, D. Schlettwein "I-V Hysteresis of Methylammonium Lead Halide Perovskite Films on Microstructured Electrode Arrays: Dependence on Preparation Route and Voltage Scale", Phys. Status Solidi A, 2016, 213, 3845.) we prepared thin
films on microstructured gold electrode arrays on Si wafers using LaMa´s cleanroom facilities. I-V characterization showed hysteresis for all samples. Persistent polarization of the perovskite films, e.g., was observed following positive or negative poling as shown in the figure. At even higher bias voltages a different kind of hysteresis loop was seen caused by migrating ions leading to a decrease in barrier width at the perovskite/metal contacts. The I-V characteristics in that larger voltage range were modeled by two opposing diodes. Time-dependent studies were performed to analyze the decay of the different observed polarization phenomena in the films during either short-circuit or continuous sweeping of the bias voltage. Consequences of such persistent polarization and barrier formation for use of the materials in solar cells were discussed. Presently we are working on an extension of this study towards detailed mechanistic investigations using dedicated experiments established in the 1st Physics Institute.