Novel thieno-[3,4-b]-pyrazine derivatives for non-doped red organic light-emitting diodes

Two novel red fluorescent thieno-[3,4-b]-pyrazine-cored molecules containing tetraphenylethylene as peripheral groups, T-TP and T-TP1, are designed and synthesized. Their photophysical, electrochemical and electroluminescent properties are investigated. They are characterized by large Stokes shifts of over 100 nm. The bulky peripheral groups enable these molecules to be well soluble and provide the site-isolation effect on the planar emissive core. These novel materials are used as non-doped emitting layer to fabricate organic light-emitting diodes (OLEDs) by vacuum evaporation technique. Saturated red emission is obtained with a maximum brightness of 1385 cd m−2 and a luminance efficiency of 0.66 cd A−1.

Graphical abstractDecorating the planar thieno[3,4-b]pyrazine emissive core with bulky tetraphenylethylene groups generates the three-dimensional non-planar fluorophors, which exhibit the best performance reported for thieno[3,4-b]pyrazine derivatives so far in their non-doped red light-emitting diodes.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Decorating thieno-[3,4-b]-pyrazine with bulky tetraphenylethylene groups generated efficient solid-state fluorophores. ► Organic light-emitting diodes were fabricated using these derivatives as non-doped emitting layers. ► Saturated red electroluminescence was obtained with best performance for thieno-[3,4-b]-pyrazine derivatives reported so far.