Conformational phase transition in a high-efficiency near-ultraviolet electroluminescent diarylpolysilane

We report on the observation of a structural phase transition in a diarylpolysilane, poly[bis(p-n-butylphenyl)silane] (PBPS), which was recently shown to emit high-efficiency room-temperature electroluminescence (EL) in the near-ultraviolet region. Spectroscopic and calorimetric experiments have revealed that this structural phase transition accompanies a conformational change in the Si-backbones of PBPS from the disorder form (lower temperature form) to the trans-planar form (higher temperature form). The spectroscopic changes induced by this structural phase transition are discussed in relation to the EL characteristics of PBPS, and found to have positive effects on them.