Boron-carbon-nitrogen films with different composition and bonding structures are grown by ion-beam-assisted deposition. The photoelectric yield from these films is used to characterize their potential use as coatings to enhance electron emission. As excitation light we used soft x rays in the course of x ray absorption experiments. In this way, we combine a detailed chemical and compositional characterization of the films with their photoelectric yield. Our results indicate that the main parameter affecting the electron emission is the proportion of sp(3) hybrids in the film.