SPLTRAK Abstract Submission
Development of Spatial Mapping and Degradation Monitoring for Perovskite Films
Emily J Miller, Biwas Subedi, Jaehoon Chung, Chongwen Li, Yanfa Yan, Nikolas J Podraza
The University of Toledo, Toledo, OH, United States

Hybrid organic-inorganic metal halide based perovskite films prepared in device relevant structures are examined by mapping spectroscopic ellipsometry measurements to determine spatial variations in structural and complex optical properties of the perovskite film. The measurements are repeated several times over the course of 48 hours in order to track changes in these properties as well as the spatial dependence in how the film degrades. Preliminary analysis of mapping and time dependent measurements of a (FAPbI3)0.95(MAPbBr3)0.05 perovskite film in a device-like structure consisting of soda lime glass superstrate / indium tin oxide top contact / PEDOT:PSS hole transport layer / perovskite film suggests that degradation is indicated by decreases in relative density of  the perovskite nucleation layers, changes in perovskite effective film thickness, and reduction in the quality of fit indicated by increases in thee the mean square error (MSE) over time when fixing the complex optical properties of the perovskite to those obtained prior to degradation.  The increase in the MSE and reduced quality of fit implies that the initial perovskite optical properties are insufficient to describe changes in the opto-electronic response during degradation occurring simultaneous to changes in the film structure. These changes vary with position from the center of the sample to the corner.  This approach develops the methodology in analyzing spatially dependent variations in perovskite materials which will be necessary during scale up for large area depositions and industrial fabrication.