蓝色有机电致发光材料OXD-7的合成及性能

Synthesis and Properties of a Blue Organic Electroluminescent Material

重点研究了蓝色有机电致发光材料OXD-7的合成路线及提高产率的方法,并用自行设计加工的升华提纯装置进行两次OXD-7的升华提纯,可使产物纯度达到99.2%。通过真空镀膜制作出结构为ITO/CuPc/NPB/OXD-7/A lq3/Mg-Ag/A l的器件,器件采用透明ITO导电玻璃作正极,依次真空蒸镀酞菁铜、NPB、OXD-7、A lq3、Mg-Ag电极,最后在合金电极上覆盖一层很薄A l膜。膜厚由频率震荡计监测,测试了器件的光电性能以及寿命,研究并讨论了材料的纯度对器件寿命的影响。

The synthesis method of OXD-7 was studied chiefly. Its synthesis step as follows： 1. Ethyl 4-tert-butylbenzoate can be prepared by the esterification reaction of 4-tert-butylbenzonic acid and ethyl alcohol, then it was reacted with hydration hydrazine to get 4-（ t-butyl）benzoyl hydrazine; 2. m-phthaloyl chloride was prepared by the reflux reaction of isophthalic Acid and thionyl chloride; 3. 4-tert-butyl benzoyl hydrazine was added to the synthesized m-phthaloyl chloride. The mixture was allowed to react at 80 ℃ for 2 h, then the mixture was cooled and then poured into ice-water. The precipitate was filtered and washed with water, dry in 100 ℃, the previous compound of OXD-7 was prepared. Finally, the previous compound of OXD-7 was put into the three-necked bottle, POCl3 and PC15 was added, heats to reflux for 5 h, the phosphorous oxychloride was removed by the distillation under a reduced pressure, filters, the residue was washed with water and recrystallized two times from ethyl alcohol to give 11.2 g of OXD-7, the purity is 97.2% by HPLC. The sublimation of OXD-7 was executed under the pressure of 35 Pa and the temperature of 300 ~C used the sublimation system designed by ourselves. After the sublimation, the purity of OXD-7 is 99.2% ,the melting point is 241.5 ℃. A blue organic electroluminescent device was fabricated and its structure is ITO/CuPu/NPB/OXD-7/ Alq3/Mg-Ag/Al. An indium-tin-oxide coated glass substrate （anode substrate） was sequentially washed in a cleaning solution, rinsed in de-ionized water and dried. Copper phthalocyanine （150）, N, N＇-bis-（ 1-naphthyl） -N, N＇-diphenyl benzidine （ 600 ）, OXD-7, alumium-tris-8-hydroxyquinoline （ 350 ） were vapor deposited in turn on the ITO glass, then Mg-Ag alloy was vapor deposited as the anode, finally, metal aluminum was vapor deposited onto the Mg-Ag alloy as the protecting layer. The device was packaged in a dry glove box full of nitrogen for protection against ambient environment. The photoelectric property and life-time of OXD-7 were tested. The influence of the material purity to the lifetime and the brightness was studied and discussed. Under 8 V drive voltage, the device gives a blue emission peaked at 472 nm, the maximal brightness is about 456 cd/m^2, the CIE coordinate of the emission color is x =0. 144 4, y =0.098 1.