Anthracene Green Fluorescent Derivatives Based on Optimized Side Groups for Highly Efficient Organic Light-Emitting Diode Emitters

Two green fluorescent materials, N,N,N′,N′-Tetra-o-tolyl-anthracene-9,10-diamine (o-Me-TAD) and N,N′-bis(2,5-dimethylphenyl)-N,N′-di-o-tolylanthracene-9,10-diamine (DMe-o-Me-TAD) including anthracene and diphenylamine moiety, were synthesized by Buchwald-Hartwig amination. In solution state, PL maximum wavelength of o-Me-TAD and DMe-o-Me-TAD is 518 nm and 520 nm. The doped device using o-Me-TAD as green fluorescent dopant exhibited CE of 19.78 cd/A and EQE of 5.97%. The doped device using DMe-o-Me-TAD as dopant exhibited CE of 22.37 cd/A and EQE of 7.02% without roll-off. Doped devices fabricated using o-Me-TAD and DMe-o-Me-TAD show the EL peaks at 522 and 523 nm corresponding to the Commission Internationale de L’Eclairage (CIE) coordinates of (0.29, 0.63) and (0.27, 0.61).

Synthesis and Electroluminescence Property of Anthracene Green Fluorescent Derivatives Based on Optimized Side Groups

Molecular size of OLED emitting materials is nano-metric size and when it is applied to the electric field it emits the light based on the energy conversion result. As new green fluorescent emitters, N,N,N',N'-Tetra-m-tolyl-anthracene-9,10-diamine (m-Me-TAD) and N,N,N',N'-Tetra-p-tolyl-anthracene-9,10-diamine (p-Me-TAD) were synthesized and the properties were evaluated. In solution state, photoluminescence (PL) maximum wavelength is 517 nm for m-Me-TAD and 529 nm for p-Me-TAD. In electroluminescence (EL) spectra, EL maximum wavelength of m-Me-TAD is 518 nm and p-Me-TAD is 533 nm. The doped device using m-Me-TAD as green fluorescent dopant exhibited current efficiency (CE) of 17.41 cd/A and external quantum efficiency (EQE) of 7.41%. The doped device with p-Me-TAD was optimized in order to achieve a green OLED with high efficiency.

Synthesis of Fluorescent Dansyl Derivatives of Methoxyamine and Diphenylhydrazine as Free Radical Precursors

Starting from dansyl-chloride, in reaction with 1,1-diphenylhydrazine and methoxyamine, two new fluorescent derivatives 1 and 2 were obtained and characterized by NMR, IR, UV-Vis, HR-MS, and fluorescence spectroscopy. The single-crystal X-ray structure was obtained for compound 2. Both compounds generate free radicals by oxidation, as demonstrated by ESR spectroscopy. Compound 1 generates the corresponding hydrazyl-persistent free radical, evidenced directly by ESR spectroscopy, while compound 2 generates in the first instance the methoxyaminyl short-lived free radical, which decomposes rapidly with the formation of the methoxy radical, evidenced by the ESR spin-trapping technique. By oxidation of compounds 1 and 2, their fluorescence is quenched.