Polarized electroluminescence from a uniaxially oriented polysilane thin film

A novel polysilane, poly[(p-butoxyphenyl)phenylsilane] (PBPPS) has been synthesized and employed as an emissive layer of an organic electroluminescence (EL) device. PBPPS was spin-coated onto a uniaxially oriented poly(diethylsilane) (PDES) ultrathin film prepared by the friction-transfer method. We observed polarized, near-ultraviolet (UV) EL with its dichroic ratio of 2 from the polysilane-based multilayered EL device. Polarization direction was found to be identical with the drawing direction of the friction-transfer process for the PDES film, indicating that PBPPS in the emissive layer was aligned parallel to the uniaxial orientation of PDES. A depolarized, broad visible band appeared in the EL spectrum, which was absent in photoluminescence of PBPPS or PDES films. Origins of near-UV and visible EL components are discussed.