Optical properties of organic/inorganic perovskite microcrystals through the characterization of Fabry-Pérot resonances

A precise knowledge of the optical properties, specifically the refractive index, of organic/inorganic perovskites, is essential for pushing forward the performance of the current photovoltaic devices that are being developed from these materials. Here we show a robust method for determining the real and the imaginary part of the refractive index of MAPbBr 3 thin films and micrometer size single crystals with planar geometry. The simultaneous fit of both the optical transmittance and the photoluminescence spectra to theoretical models defines unambiguously the refractive index and the crystal thickness. Because the method relies on the optical resonance phenomenon occurring in these microstructures, it can be used to further develop optical microcavities from perovskites or from other optical materials. Fabry-Pérot oscillations modulating the optical transmission and photoluminiscence spectra of hybrid perovskite microcrystals have been characterized. The simultaneous fit of both spectra to theoretical models permits to determine optical properties.