Optical Properties of Organic Inorganic Metal Halide Perovskite for Photovoltaics

摘要

We have described the use of the Kramers-Kronig method for the analysis of reflectance spectra. Using this method, we have reported the optical and dielectric properties of organic-inorganic metal halide perovskite thin films. We prepared thin films by spin coating a mixture of PbI₂ and MAI dissolved in DMF and DMSO in 4:1 volume ratio. We measured energy (or wavelength) dependent reflectance spectra R(v) of thin films using UV/Vis/NIR spectrophotometer. We also calculated phase of reflected waves (θ(v)) using Kramers-Kronig dispersion relation. Finally, using θ(v)and R(v), we investigated optical and dielectric constants as well as absorption coefficient in UV/Vis/NIR spectral region. In our study, we found that n(v) and ε₁(v)follow similar pattern to that of R(v). Three oscillators in k(v) and ε₂(v)are found similar to the ones obtained from ellipsometry study. As expected, α(v) calculated from R(v)are very high of the order of 10⁵ cm^-1 in the visible and ultraviolet regions.