Structure–property relationships of star-shaped blue-emitting charge-transporting 1,3,5-triphenylbenzene derivatives

• Three new blue-emitting derivatives of 1,3,5-triphenylbenzene were synthsized.
• Chromophores in the synthesized compounds are connected via different linkages.
• The highest fluorescence quantum yield was shown by compound with ethenyl-bridge.
• Hole mobility of the layers reached 2.4 × 10−3 cm/Vs at high electric fields.

Three star-shaped derivatives of 1,3,5-triphenylbenzene bonded to fluorene moieties with various linking groups were designed and synthesized. The three dendritic compounds are characterized by high values of decomposition temperature (up to 434 °C) and form glasses with glass transition temperatures ranging from 55 to 75 °C. The star-shaped compounds emit light in the deep blue region (385–412 nm) and their solutions exhibit moderately high fluorescence quantum yields in the range of 0.40–0.54. The obtained molecules show relatively small values of the optical gaps ranging from 2.50 to 3.08 eV. The layers of the compounds exhibit hole mobility values in the range of 4.9·10−4–2.4·10−3 cm2/V s at electric field 1·105 V/cm. A comparative study of the experimentally estimated and theoretically calculated (DFT method) characteristics of the 1,3,5-triphenylbenzene showed that the geometry, optical and electrochemical properties of the star-shaped molecules depend on the degree of conjugation and the nature of the linking bridge.

Figure optionsDownload as PowerPoint slide