Intraband Absorption Coefficient in Organic-Inorganic Hybrid Nanocomposite-A Pathway to Room-Temperature, Mid- and Long-Wavelength Infrared Detection

Size reduction in materials into nanometer range leads to discrete energy levels depending on the size of the structure. Control over dimensions as well as the composition of structures makes it possible to tailor material properties for specific applications. Colloidal quantum dots (CQDs) are solution phase processed nanostructure, which are coated with a surface ligand material that is comprised of short, organic molecules to prevent the CQDs from aggregation when placed in solution. In fact, mostly, they are embedded in a matrix material, which necessarily affects the electronic levels of the nanostructure. Hybrid nanocomposite is mainly composed of inorganic CQDs embedded in an organic conjugated polymer. In this paper, we present a method for calculating the electronic structure, such as intraband energy levels and wave functions in a hybrid nanocomposite thin-film structure. This model converts the Schrödinger equation into a matrix equation, which can be easily solved by programming languages. Moreover, based on the model, optical intraband absorption coefficient for an embedded CQD into conducting polymer is calculated and compared with experimental data. Our analysis shows that hybrid nanocomposite can be considered as a good candidate for absorber material in mid- and long-wavelength infrared detectors. In addition, the impact of the CQD average size is also studied as design parameter on the absorption spectra of the hybrid nanocomposites. The model is verified by comparing the results with reported data in the literature.