Using the solution absorbance extracted dielectric function of CuInS₂/ZnS quantum dots to model optical properties of well-ordered Langmuir-Schaefer thin films

Abstract

The complex dielectric function of any materials system is important fundamental knowledge. This paper will explore a method for determining the intrinsic complex dielectric function of CuInS2/ZnS core/shell quantum dots from an absorbance measurement of the QDs in solution using an iterative error minimization method employed by Dement et al. for core/shell QDs [1]. The Bruggeman effective medium approach can be used to effectively model thin films of these QDs using the absorbance extracted intrinsic dielectric function. The modeled dielectric function of these films agrees well with ellipsometrically determined dielectric functions of Langmuir-Schaefer deposited thin films. While energy gap values and other optically accessible information have been reported, to the best of our knowledge this is the first time the intrinsic complex dielectric function of CuInS2/ZnS QDs and the dielectric functions of these materials in highly ordered thin films has been explored.