کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1410705 | 1501893 | 2007 | 10 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Synthesis and characterization of 1,3,4-oxadiazole derivatives containing alkoxy chains with different lengths Synthesis and characterization of 1,3,4-oxadiazole derivatives containing alkoxy chains with different lengths](/preview/png/1410705.png)
The synthesis, optical properties, electrochemical properties, electronic structures and applications in electroluminescent device of three series of 1,3,4-oxadiazole derivatives, 1,4-bis[(4-methylphenyl)-1,3,4-oxadiazolyl]phenylene (OXD1), 5,5′-di-(4-methyl)-2,2′-p-(2,5-bisalkoxyphenylene)-bis-1,3,4-oxadiazole (OXD2–n) and 1,4-bis[(4-alkoxyphenyl)-1,3,4-oxadiazolyl]phenylene (OXD3–n) are reported. The molecular structures of the oxadiazole compounds were confirmed by FT-IR, 1H NMR spectroscopy and elemental analysis. The optical and electrochemical properties of the compounds were investigated by UV–vis absorption and photoluminescence spectroscopy as well as cyclic voltammetry. The results show that introduction of two alkoxy groups whose electron-donating ability is stronger than that of methyl groups increases the electron density of the conjugated segment of OXD2–n (with side-on alkoxy substituents) and OXD3–n (with end-on alkoxy substituents), and thus leads to the absorption maximum bathochromic-shift compared to that of OXD1. The HOMO and LUMO energy levels of the compounds studied are in the range of −2.78 to −2.89 and −5.75 to −6.20 eV. Calculations on the representative compounds by the Dmol3 package of MS Modeling 3.0 revealed that the increase of energy levels in both OXD2–n and OXD3–n was due to the change of the frontier molecular orbital distribution in the central benzene ring. The light-emitting devices have been fabricated using blends of MEH-PPV and these compounds as emissive layers, among which, maximum brightness up to 11810 cd m−2 (8.5 V) has been observed, which is 40 times brighter than that with MEH-PPV. The result of the devices suggested that oxadiazole derivatives studied function well as electron-transporting materials and can be used in LEDs, and thus to enhance the efficiency of LEDs.
Journal: Journal of Molecular Structure - Volume 846, Issues 1–3, 26 November 2007, Pages 55–64