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

We report the basic device characteristics of light-emitting diodes (LEDs) 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 LEDs 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 LEDs 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-LEDs or UV-LEDs based on polysilanes are discussed in terms of the fundamental properties of polysilanes and the device structure