| Summary: | 碩士 === 國立交通大學 === 應用化學系所 === 97 === Abstract
This thesis consists of two sections. In section A we discuss the synthesis and characterization of bipolar hosts for blue electrophosphorescent devices; while in section B we discuss pyrazine-containing polymers as red emitter in electroluminescent devices.
In section A, we have synthesized two bipolar hosts applicable in electrophosphorescent devices, namely 9-(3-(5-(4-tert-Butylphenyl)-2- oxadiazoyl)phenyl)-9-(4-diphenylaminophenyl)-fluorene (for the sake of convenience, we will abbreviate this as TPA-F-OXD from now on) and 9-(3-(5-(4-tert-Butylphenyl)-2-oxadiazoyl)phenyl)-9-(9-phenyl-9H-carbazol-3-yl)fluorene (abbreviated Cz-F-OXD from now on). The former material uses triphenylamine as the hole transporter grouped with an oxidiazole group to produce the bipolar characteristic in the material; while the latter uses a 9-phenylcarbazole/oxidiazole group combination to produce the same characteristic.
In molecular design, the C-9 atom in fluorene bridge electrons/holes transporting groups via sp3 orbitals preventing the increment of conjugation length. Hence, we can acquire bipolar host with a triplet energy gap (ET) of 2.74 eV: TPA-F-OXD, Cz-F-OXD. This ET is higher than the commonly used blue phosphorescent dopant material- iridium(III)bis[(4,6-difluorophenyl)-pyridinato-N,C2’]picolinate（FIrpic, ET = 2.62 eV). When we use TPA-F-OXD and Cz-F-OXD doped with 7wt% FIrpic as the emitting layer, we obtain a maximum external quantum efficiency of 17.5% and 14.7%, maximum luminous efficiency of 32.1 cd A-1 and 26.3 cd A-1, and a maximum power efficiency of 28.9 lm W-1 and 18.3 lm W-1 respectively.
In section B, the novel blue-light-emitting polymers with electron transporting group and triphenylamine pendant groups attached at the C-9 position of the fluorine was synthesized. PYFTPA with both pyrazine and triphenylamine groups demonstrate satisfactory charge injection and charge transporting ability. We then insert a narrow band gap material (DBT) into the polymer. Thus we have obtained a series of polymers named PYFTPA-DBT. Devices based on these polymers emit a saturated red light with Chromaticity coordinates around x = 0.66, y = 0.34. The device using PYFTPA-DBT10 as the emitting layer achieved a maximum efficiency of 1.29% and maximum power efficiency of 0.63 lm W-1.
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