Localization of the Wannier–Mott Exciton on a Langmuir-Film/CdS Organic Semiconductor Interface

Abstract

The low-temperature (T = 2 K) light reflectance spectra of organic semiconductor structures produced by depositing Langmuir–Blodgett films on a cadmium sulfide (CdS) crystal surface are studied. The spectra were studied in the region of the resonant frequency of the exciton state A_n = 1 in CdS. The spectra were analyzed within a multilayer medium model with allowance for the spatial dispersion and an exciton-free “dead” layer near the crystal surface contacting with the film. A conclusion is made that, as a result of the deposition of an organic film on a semiconductor crystal surface, the Wanier–Mott exciton is spatially localized near the film–crystal interface.