Highly polarised electroluminescence in low aspect ratio mesogenic molecules

Abstract

We have synthesised the low aspect ratio mesogenic compounds containing one fluorene and two biphenyl moieties, and investigate their mesomorphic properties and the resultant anisotropic properties in both photoluminescence and electroluminescence. We introduced pentyloxy as a terminal flexible group in order to guarantee formation of mesophase and varied the lateral flexible group from propyl to octyl to control the mesogenic transition temperature. Eventually, in spite of the low aspect ratio mesogen, high polarisation ratio (PR) was achieved by spin-coating of luminescent nematogenic molecules. Furthermore, the PR was significantly enhanced by the additional thermal annealing process.