This document describes techniques and apparatuses for implementing backlight dimming film. These techniques may be performed using a side entry lightguide structure having a receiving side and an output surface. The lightguide structure receives light through the receiving side and redirects the light so that it is output through the output surface. The techniques are also performed relative to a cover screen structure that receives light from the output surface of the lightguide structure and filters the light to display an image. A dimming film is disposed between the output surface of the lightguide structure and the cover screen structure. The dimming film is controlled to block light output from the output surface of the lightguide structure from being received at the cover screen structure.