Near-ultraviolet light-emitting diodes based on σ-conjugated linear silicon-backbone polymers

We report the basic device characteristics of light-emitting diodes (LED's) based on linear silicon-backbone polymers, polysilanes, with a view to the possibility of employing them as an emissive material in a solid-state light source in the near-ultraviolet (NUV) or ultraviolet (UV) region. The LED's we fabricated have a single-layer structure consisting of a thin film of polysilane polymer, together with an indium-tin-oxide (ITO) and metal electrode for the injection of holes and electrons, respectively. The device characteristics of these LED's depend strongly on the nature of the polysilane, reflecting its chemical, optical and electronic properties. Efforts to optimize the emissive polysilane have led to the successful fabrication of single-layer LED's that emit NUV light of 407 nm (3.05 eV) with a quantum efficiency of 0.1% photons/electron and a spectral bandwidth of less than 15 nm (0.11 eV) at room temperature (RT), Future improvement in the device characteristics of NUV-LED's or UV-LED's based on polysilanes are discussed in terms of the fundamental properties of polysilanes and the device structure.