Chapters authored
Spectroscopic Ellipsometry Study of Organic-Inorganic Halide: FAPbIxBr3−x Perovskite Thin Films by Two-Step Method
Spectroscopic ellipsometry (SE) was used to investigate the role of isopropyl alcohol (IPA) solvent in the synthesis of organic-lead-halide perovskite CH(NH2)2PbIxBr3−x [FAPbIxBr3−x] thin films including the effect of I/Br composition ratio by the two-step reaction of an amorphous (a-)PbIxBr2−x layer and FAIxBr1−x solution diluted in IPA. An optical dispersion model was developed to extract the complex refractive index N (=n + ik), optical transition, and film thickness of FAPbIxBr3−x perovskites by SE analysis at different I/Br composition ratio as a function of immersion time in a solution of FAIxBr1−x diluted in IPA. SE combined with X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) revealed that Br incorporation into films promoted the densification of FAPbIxBr3−x perovskite network along with increased film thickness and volume fraction of void. IPA promoted film crystallization of a-PbIxBr2−x accompanied by the formation of surface roughness, grain boundaries, and voids, followed by enhanced diffusion of FAIxBr1−x into the grain boundaries/voids in the mesoporous crystallized PbIxBr2−x network. These processes contribute synergistically to the growth of the perovskite structure.
Part of the book: Ellipsometry