Optical constants of multilayered colloidal ZnSe nanoparticles

•Layer-by-layer preparation of composite films of colloidal ZnSe nanoparticles.•Dependence of films’ refractive index on ZnSe nanoparticle size owing to quantum size.•Refractive index control of thin films by size of semiconductor nanoparticles.•Adjustment of thin film thickness by layering nanoparticles for optical thin films. The purpose of this study was to prepare multilayered films of colloidal ZnSe nanoparticles (NPs) and investigate their optical constants. Thin films comprising multilayered ZnSe–NPs were prepared on a SiO2 substrate using the layer-by-layer (LbL) method. The samples were studied using spectroscopic ellipsometry in the range of 0.75–3.20 eV. The film thickness increased linearly with the number of layers of colloidal NPs, and the prepared films were optically homogeneous. Furthermore, the refractive index of the ZnSe–NP films varied depending on the NP size owing to the quantum-confinement size effect. Multilayered ZnSe–NP films deposited using the LbL method are particularly useful as optical thin films because they can help control the film thickness and refractive index. It is expected that thin films with various refractive indices and corresponding dispersions can be produced using other semiconductor NPs and combinations thereof.