Synthesis of thermally stable and hole-transporting amorphous molecule having four carbazole moieties

A novel thermally stable and hole-transporting amorphous molecule, 9,9-bis(4-[bis-(4′-carbazol-9-yl-biphenyl-4-yl)-amino]-phenyl)fluorene (T-Caz) has been synthesized in two-step reactions from carbazole. T-Caz showed UV-Vis absorption bands at 290 and 340 nm in chloroform solution, and the photoluminescence spectrum showed a maximum peak at 420 nm in a purplish blue region. Differential scanning calorimetry (DSC) showed a high glass transition temperature at 250 °C. The organic light-emitting device prepared by spin-coating T-Caz solution onto the indium-tin oxide (ITO)-coated glass substrate in conjunction with tris(8-quinolinolato)aluminum (Alq) and LiF/Al, as an electron transporting light-emissive layer and a metal cathode, respectively, showed a maximum luminescence of 10,300 cd/m2 at 11 V.