The Research And Fabrication Of White Organic Light-Emitting Diodes

Nowadays, WOLEDs(white organic light-emitting diodes) that have a promising future can be used not only as flat illumination light sources but also as full color displays combined with color filters. During the manufacture of WOLEDs, the technics of doping and photolithography are very important, so the study of WOLEDs attracts world wide attention in the fields of science and industry due to their many merits.In order to make clear the manufacture technics,the electrolumi -nescent mechanism and the configuration of WOLEDs, firstly, we did a series of relatived experiments on exposure and photolithography,and studied t`e photolithography on 96×64 matrix OLED panel and the cathode separation's photo-etching technics in detail,and found the optimal technics parameters.In order to improve the efficiency and CIE coordinates,based on the mechanism of mixing colors we gained the best brightness ratio of trico -lor when mixed into standard white light of( 0.33,0.33) in WOLED:28.2% for red light,57.1% for green light and 14.7% for blue light, which provides certain foundation for experiments.We adopted DCJTB and TBPe to make two homochrom(ered,blue) OLEDs as the red and blue dyes, the configurations are respectively as follows: ITO/CuPc(15nm)/NPB(50nm)/Alq3(30 nm):rubrene(x): DCJTB(6.1)/Alq3(30nm)/LiF(1nm)/Al(100nm),(x=2,3.7,4.2,5 nm,the dopped concentration is 1.1%,2.1%,2.3% and 2.8% respective -ly) for red OLEDs and ITO/CuPc(150 nm)/NPB(500 nm)/ADN(300 nm):TBPe(30 nm)/Alq3(350 nm)/RbF(20 nm)/Al(1,000 nm)for blue OLED. We discussed the electroluminescent mechanism and the infection of the dopped concentration of rubrene on the perform -ances of red OLEDs; And after a lot of designments and manufactures we found an integrated and reasonable scheme,and carried out some test -ings and discussions on the characteristics of current -voltage curve, efficiency- voltage curve and luminescence-spectrum curve and so on.Subsequently,we made two kinds of WOLEDs.In the first experiment we used the red light-emitting layer"Alq3:DCJTB"and the blue light-emitting layer"ADN:TBPe"together to realize white display,its configuration is as follows: ITO/CuPc(15nm)/NPB(50nm)/ADN:TBPe(15nm)/Alq3:DCJTB(15nm)/Alq3(35nm)/LiF(2nm)/Al(100nm); In the second experiment, we adopted the configurature with single emitting layer"ITO/CuPc ( 15nm ) /NPB ( 50nm )/Alq3:TBPe:DCJTB(30nm)/Alq3(35nm)/LiF(2nm)/Al(100nm)"to produce white light. The research found the first method was the best because of its simple manufacture,easy repeatment,stable and better chroma and smaller fluctuation with the alteration of voltage.Its CIE coordinate i(s0.3345,0.333),close to that of standard white light,which approches the advanced level of WOLEDs in the worldwide.Finally,we made a kind of WOLEDs with good chroma successfully by the method of red,green and blue light-emitting layers,its configuration is as follows:ITO/CuPc(10nm)/NPB(40nm) /ADN(50nm),3%TBPe/Alq3(30nm)/Alq3(30nm),1%DCJTB)/Alq3( 30nm ) /Mg:Ag ( 10:1,150nm ) $the CIE coordinate approaches(0.333,0.3398), colour temperature is 4,258.2℃.Obviously, the several methods are suitable for WOLEDs and can be used to improve their performance.