ELECTROLUMINESCENCE OF A BICHROMOPHORIC MOLECULE WITH A BENZOXYAZOLYLCOUMARIN AND CARBAZOLE MOIETY

The electroluminescent properties of a bichromophoric molecule in whic h a benzoxyazolylcoumarin and carbazole moiety is combined with 1,2-et hylene linkage, i.e. benzoxyazolyl)-7-[2-(9-carbazolyl)ethoxy]-coumari n (CmCz), were investigated. CmCz exhibits fluorescence of different c olors in a solid state and solution. Two types of device were made. On e consisted of a vacuum vapor-deposited film of CmCz as an emission la yer to utilize fluorescence in the solid state; the second consisted o f a spin-cast film doped with CmCz as an emission material to utilize fluorescence in the solution. The device with a vapor-deposited CmCz f ilm between electrodes shows a green emission with a luminance of less than 10(-2) cd/m(2). The multiple layer device in which the CmCz film was sandwiched between a hole transport layer and electron transport layer showed a green emission whose spectrum is identical to the photo luminescent spectrum in the vapor-deposited CmCz film. A maximum lumin ance of the multiple layer device is about 5000 cd/m(2). On the other hand, the devices consisting of a spin-cast film containing a hole tra nsport material, an electron transport material and CmCz showed a blue emission whose spectra a are identical to the photoluminescent spectr um of CmCz in chloroform. Luminance of these devices is over 100 cd/m( 2). (C) 1997 by John Wiley & Sons, Ltd.