Complex Refractive Index Spectrum of CsPbBr₃ Nanocrystals via the Effective Medium Approximation

We have estimated the intrinsic complex refractive index spectrum of a CsPbBr₃ nanocrystal. With various dilute solutions of CsPbBr₃ nanocrystals dissolved in toluene, effective refractive indices were measured at two different wavelengths using Michelson interferometry. Given the effective absorption spectrum of the solution, a full spectrum of the effective refractive index was also obtained through the Kramers-Krönig relations. Based on the Maxwell-Garnett model in the effective medium approximation, the real and imaginary spectrum of the complex refractive index was estimated for the CsPbBr₃ nanocrystal, and the dominant inaccuracy was attributed to the size inhomogeneity.