NEAR-ULTRAVIOLET ELECTROLUMINESCENCE FROM POLYSILANES

We report the electroluminescent (EL) characteristics of a new class o f polymeric material, polysilanes, which were employed in Light-emitti ng diodes (LEDs) as an emissive material. In contrast to the LEDs util izing pi-conjugated polymers and small molecules that have been report ed to date, LEDs made from polysilanes exhibit EL in the near-ultravio let (NUV) or ultraviolet (NUV) region due to their sigma-conjugation. Three types of polysilanes, dialkyl, monoalkyl-aryl and diaryl polysil anes, have been used as the emissive material, together with an indium tin-oxide (ITO) and metal electrode for the injection of holes and ele ctrons, respectively. The LED characteristics were observed to depend strongly on the chemical, optical and electronic properties of the emi ssive polysilanes. The development of emissive polysilanes has led to the successful fabrication of single-layer LEDs which emit NUV light a t 107 nm (3.05 eV) with a quantum efficiency of 0.1% photons/electron at room temperature. (C) 1998 Elsevier Science S,A. An rights; reserve d.