Abstract
The relationships between molecular structures and properties of organic electroluminescent (EL) devices were investigated by oligothiophene derivatives (TD). Both the peak wavelengths of absorption and photoluminescence of TD increased with increasing number of thiophene rings. The TD were evaluated in two types of layered organic EL devices. In type 1 device, TD was used as an emitting hole transport material, and an oxadiazole derivative was used as an electron transport material. The EL spectra of type 1 devices originate from the TD, and shift to the longer wavelengths with increasing number of thiophene rings. In type 2 device, TD was used as a hole transport material, and tris(8-hydroxyquinoline)-aluminum (Alq3) was used as an emitting electron transport material. The luminous efficiency of type 2 device was higher than that of type 1 device. In the case of type 2 device, the EL spectra were originate from the TD and Alq3. The results were explained by energy diagram.
Published Version
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