We have carried out a numerical study of the structural, thermodynamic and optical properties of the partially fluorinated 5-n-alkyl-2-(4-n-(perfluoroalkyl-metheleneoxy)phenyl) free-standing smectic film in air under the action of the external electric field E. Calculations, based upon the extended McMillan's mean-field theory with anisotropic forces, show a stepwise reduction of the value of the Helmholtz free energy and the reflectivity of the partially fluorinated smectic film in air, as the temperature is raised above the bulk smectic-A-isotropic transition value. It has been shown, by solving the self-consistent nonlinear equations for the orientational and translational order parameters, that the electric field E may not only affect the layer-thinning transition sequences, but also change the first multilayer jump in the film thickness, whereas practically does not affect the reflectivity of the partially fluorinated smectic film in air. The partially fluorinated LC compounds reveal a compression of a smectic layer spacing during the layer-thinning transitions which is supported by the negative values of the thermal expansion coefficient. (C) 2016 Elsevier B.V. All rights reserved.