Morphological study of lead halide perovskites cast at different spin velocities.
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Date
2024
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Publisher
Universidad de Concepción
Abstract
The present work centers on the use of dynamic scaling theory when dealing with processes which do not depend on deposition times. Our hypothesis is that through film thickness one can successfully calculate the critical exponents of a system, classifying it and understanding the role that the controlled variable dominating the material dispersion process has on structure formation. This hypothesis was tested by studying the effects of spin velocity on film morphology for lead halide perovskite, synthesized by way of spin-coating, setting different top speeds at 600, 700, 800, 900, 1000, 1500 and 2000[RPM]. The first part of the document deals with the theory of semiconductors in order to understand what type of material we are working with and the characterization method of X-ray diffraction. Then, a chapter is dedicated to dynamic scaling theory which is the base of our statistical analysis and the main part of our hypothesis, since is how we calculate the critical exponents. Finally, the results obtained from X-ray diffraction, sample imaging, statistical analysis of the films and computed critical exponents are shown in the fifth chapter, where we compare the use of different statistical tools, specifically the auto-correlation function, heigh-height correlation function and the software WSXM. When it comes to the specific characterization techniques, tetragonal phase perovskite fabrication was confirmed thanks to X-ray diffraction, with the spin velocity having an slight effect on crystallite size. Atomic force microscopy was used for sample imaging and profilometry, done at our laboratory, with the statistical analysis of height distribution done using Dynamic scaling theory. We successfully obtained exponents which correspond to a one dimensional KPZ system, proving our hypothesis correct when it comes to the use of thickness instead of time for dynamic scaling analysis.
Description
Tesis presentada para optar al grado de Magíster en Ciencias con Mención en Física
Keywords
Perovskite materials, Solar cells, Lead halides, Morphology