PDLC films (Polymer Dispersed Liquid Crystals) can be used in the construction of electrically switchable architectural windows (smart windows). In the last decade many efforts have been devoted in this field by the industries in order to optimize and commercialize a product based on PDLC materials for the building industry. For this application, the main properties that should be controlled in the PDLC film fabrication to obtain a high quality product are the haze and the opacity. In the present work we show how it is possible to modify the phisical properties of a commercial liquid crystal by adding an isotropic component in order to improve the electro-optical performances of PDLC films containing a given polymer matrix. In particular, a considerable reduction of both normal and off-axis haze can be obtained by properly selecting the chemico-phisical properties of the component added to the liquid crystal mixture.