Molecular structure and packing of various organopolysilanes having symmetrical side-chains of alkyl substituents, such as poly(dimethyl silane). poly(di-ethyl silane), poly(di-propyl silane), poly(di-butyl silane), poly(di-pentyl silane), and poly(di-hexyl silane), are examined, and thr method of orientation control of the polysilane thin film is proposed. The application of the evaporated film to the electro-luminescent device is also demonstrated.