The Investigation Of White Qrganic Light-emiting Device

White organic light-emitting device (white OLED) has potential of producing highlyefficient saturated white light, with advantages of low-driving voltage, large area availability,and flexible display, hence presenting tremendous potential applications in solid state lightingand display industry. However, the highly cost and unstable performance seriously limit theirindustrial progress. Upon these issues, this thesis mainly focuses on:Firstly, summarizing the architectures to obtain white OLED and the approaches to improvethe performance. The architectures of white OLED mainly include: single emission layer,multilayer, down-conversion, stacked OLED and etc. To improve the performance of whiteOLED, the approaches involve making use of the triplet exciton, improving the carrier injectionefficiency, balancing the transport property of carrier, and using the light extraction techniques.Secondly, grasping the OLED industrial process, which consists of substrate preparation,plasma pretreatment and vacuum deposition. Also, the performance standards of white light andmeasurement method have been presented. Furthermore, the process parameters of the standarddevices NPB/Alq3/LiF/Al have been optimized. The parameters are those with 200 W RF power,the plasma treatment of substrate is 30 s; the thickness of LiF layer is 1 nm; the thickness of eachlayer and the evaporation rate should be in control.Thirdly, on the basis of fluorescent materials and doping technology, high efficient andlarge area white OLED has been fabricated. The device architecture is: NPB(50 nm)/NPB(100nm):rubrene(2%)/ADN (30 nm):DSA-Ph(8%)/Alq3(20 nm)/Mg(150 nm):Ag(30 nm).At 20mA/cm2, the driving voltage is 8.2 V with the CIE coordinates of (0.33,0.37), luminance isbrighter than 1000 cd/cm2, and the current efficiency is 7.02 cd/A.Finally, based on the aggregation-introduced emission (AIE) system, non-doped whiteOLEDs have been obtained. The device architecture is: NPB(60 nm) /OTB(2 nm)/B4AC(1nm)/TPBI(40 nm)/LiF(1 nm)/Al(80 nm). With the increase of driving voltage, the efficiency andcolor changes slightly. The inserted OTB layer after B4AC forming quantum well expands theexciton's recombination zone. The maximum efficiency is 2.2 cd/A, and the CIE coordinates are(0.32, 0.33) at 300 mA/cm2.