| With the tremendous input on the research of OLEDs, the organic electroluminescence technology develops rapidly in aspects of the luminescence efficiency, lifetime and device technique. The OLEDs with the advantage of low energy consumption, low cost, good viewing angle, flexibility, and short response time have been applied in the field of display and solid-state lighting.The light emitting materials are of vital importance to OLEDs. Among RGB light-emitting materials, luminous efficiency, color purity, lifetime and so on of blue light-emitting materials are needed to be further improved compared with green and red light-emitting materials. Helicenes with long alkyl chain is a new type of light-emitting materials. Helicenes is a kind of polycyclic aromatic compounds with a non-palnar screw-shaped skeleton formal by ortho-fused aromatic rings. The non-planar twisted structure not only effectively reduces the degree of n conjugate, but also facilitates to form a amorphous thin film. Furthermore, the non-planar structure can also effectively prevent π-π intermolecular interaction.In this thesis, we synthesized three kinds of new helicene compounds, The [6] helicene based on fluorene with the abbreviation FINp was first reported. Fluorene and naphthalene derivatives was used as starting materials to synthesis FINp using a series of classic reactions, including Photocyclization(yield 76%). The FINp was confirmed by1H NMR,13C NMR, HRMS, MALDI-TOF, FTIR, and UV-Vis. TG-DSC, PL spectral, theoretical calculation and device properties also measured. FINp crystal belong to P21/c space group, and the molecular structure is spiral. The dihedral angle between fluorene and naphthalene is 27.6 °. The thermal measurement showed that the melting point of FINp is 87.4 ℃, and its decomposition temperature is 286.0 ℃. FINp was founded to have a quasi-reversible redox process. The HOMO energy level is-4.914 eV, and the LUMO energy level is-1.954 eV. Emission peaks of FINp were located at 390 nm,411 nm,435 nm, and PL quantum yields of FINp in solutions range from 16% to 33% while that of the film is 8%. The theoretical calculation of absorption and emission spectra is consistent with the measurement results. Non-doped and doped devices are of following structures:ITO/NPB (50 nm)/FINp or mCP:10% FINp (30 nm)/Bphen (20 nm)/Mg:Ag (150 nm)/Ag (50 nm). The device using FINp as the host emitting material has the turn-on of 6.1 V, Maximum brightness of 1900 cd/m2, Maximum current efficiency of 0.50 cd/A, electroluminescent peak of 456 nm, CIE coordinates of (0.162,0.162) and the largest external quantum efficiency of 0.76%. The device using FINp as the guest emitting material has the turn-on of 6.7 V, Maximum brightness of 4853 cd/m2, Maximum current efficiency of 0.86 cd/A, electroluminescent peak of 444 nm, CIE coordinates of (0.156,0.093) and the largest external quantum efficiency of 1.09%.Fluorene and carbazole derivatives was used as starting materials to synthesis the FICz which has aggregation induction effect (AIE) using a series of class reactions, including Photocyclization. We have carried out the FICz’s characterization and performance measurenent. FICz was crystallized in Pbca space group, with its spiral molecular structure. The dihedral Angle of fluorene and carbazole is 27.6°. Thermal tests show that FICz’s melting point is 162.5 ℃, decomposition temperature is 323.0 ℃. FICz was founded have a quasi-reversible redox process. The HOMO energy level is-4.95 eV, LUMO’s energy level is-2.63 eV. Emission peaks of FICz are located at 408 nm and 433 nm. The PL quantum yields in solutions range from 10% to 14%, while that of the film is as high as 14%. This is due to the screw of the flat structure which can prevent effectively prevent π-π intermolecular interaction, and thus prevent the solid fluorescence quenching. Non-doped emitting device structure is ITO/NPB (50 nm)/FICz (30 nm)/Bphen (20 nm)/Mg:Ag (150 nm)/Ag (50 nm). The non-doped device has the turned-on voltage of 5.8 V, and maximum current efficiency is 0.24 cd/A, CIE coordinates (0.179,0.179). Doped emitting device structure is ITO/NPB (50 nm)/mCP:10% FICz (30 nm)/Bphen (20 nm)/Mg:Ag (150 nm)/Ag (50 nm). Which has the turned-on voltage of 6.0 V, maximum brightness is 2700 cd/m2, maximum current efficiency is 0.75 cd/A. Electroluminescent peak was located at 436 nm, CIE coordinates is (0.157,0.150) and the maximum external quantum efficiency is 0.75%.The helicene of DThCz through the Suzuki reaction to introduce thiophene substituent into Diaza[7]helicene. The decomposition temperature of DThCz is 221.0 ℃. DThCz was foundto have a quasi-reversible redox process. The HOMO energy level of -5.088 eV and LUMO energy level of -2.09 eV. The emission peak are 456 nm and 483 nm. Doping electroluminescent device structure is demonstrated as follows:ITO/NPB (50 nm)/CBP:10% DThCz (30 nm)/Bphen (20 nm)/Mg:Ag (150 nm)/Ag (50 nm). The device has the turned-on voltage of 6.7 V, maximum brightness is 2302 cd/m2, maximum current efficiency is 0.70 cd/A at 10 V, Electroluminescent peak was found to be located at 460 nm, with CIE coordinates of (0.176,0.176) and the maximum external quantum efficiency of 0.41%。... |
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