Determination of the complex refractive index and optical bandgap of CH3NH3PbI3 thin films

• Autores: Guerra, J. A., Tejada, A., Korte, L., Kegelmann, L., Tofflinger, J. A., Albrecht, S., Rech, B., Weingartner, R.
• Formato: artículo
• Fecha de Publicación: 2017
• Institución: Consejo Nacional de Ciencia Tecnología e Innovación
• Repositorio: CONCYTEC-Institucional
• Lenguaje: inglés
• OAI Identifier: oai:repositorio.concytec.gob.pe:20.500.12390/2887
• Enlace del recurso: https://hdl.handle.net/20.500.12390/2887; https://doi.org/10.1063/1.4982894
• Nivel de acceso: acceso abierto
• Materia: General Physics and Astronomy; http://purl.org/pe-repo/ocde/ford#2.11.02

We report the complex refractive index of methylammonium lead iodide (CH3NH3PbI3) perovskite thin films obtained by means of variable angle spectroscopic ellipsometry and transmittance/reflectance spectrophotometry in the wavelength range of 190 nm to 2500 nm. The film thickness and roughness layer thickness are determined by minimizing a global unbiased estimator in the region where the spectrophotometry and ellipsometry spectra overlap. We then determine the optical bandgap and Urbach energy from the absorption coefficient, by means of a fundamental absorption model based on band fluctuations in direct semiconductors. This model merges both the Urbach tail and the absorption edge regions in a single equation. In this way, we increase the fitting region and extend the conventional (αℏω)2-plot method to obtain accurate bandgap values. © 2017 Author(s).