Synthesis Of A New Iridium Complex And Fluorescent/Phosphorescent OLED Study

As a new type of display and lighting technology, organic light emitting devices(OLEDs) have been widely concerned by the academic and industry circles because of its advantages of self-luminous, fast-response, low cost and so on. OLEDs can be classified into fluorescence and phosphorescence OLED(PhOLED) depending on the material of light emitting layer. According to contemporary principle, contrary to the limitation of about 25% internal quantum efficiency(IQE) in typical fluorescent OLEDs, 100% IQE can be achieved in both phosphorescence and thermal activated delayed fluorescence(TADF) OLEDs, showing their promising futures for applications. This thesis contains the study of OLED based on PhOLED or TADF mechanism, and can be devided into three parts.First, the systhesis of Ir(Npppya)3. Based on C^N=N type ligand, through the introduction of good hole transport moiety of 2-phenyl-naphthylamine, a new iridium complex is obtained. Then photophsical, and electrochemical properties are investigated. Results show that the PL(photoluminescence) peak of this mertial is at 557 nm. The highest occupied molecular orbital(HOMO) and the lowest unoccupied molecular orbital(LUMO) is-5.34 eV and-3.11 eV. The photoluminescence quantum yield is as high as 0.95. Additionaly, thermal stability of this material is good. All these features suggest its promising potential for PhOLED application.Secondly, the investigation of PhOLED based on Ir(Npppya)3. Using the system of host and guest, diodes with the structure of ITO/NPB(40 nm)/CBP:x% Ir(Npppya)3(30 nm)/BCP(8 nm)/Alq(30 nm)/LiF(1 nm)/Al are fabricated, with CBP(4,4’-N,N’-dicarbazole-biphenyl) as host material and the new iridium complex as guest material. As a result, the performance is found to be the best when the doping concentration of phosphorescent material is 6%. Then, diodes with co-host material are studied. It is found that with the structure of ITO/NPB(40 nm)/TCTA(10 nm)/mCP(10 nm)/mCP: B3PYMPM: Ir(Npppya)3(1: 1, 6%, 15 nm)/B3PYMPM(20 nm)/LiF(1 nm)/Al, the diode shows the best performance with maximum current efficiency and the maximum power efficiency of 14.26 cd/A and 5.79 lm/W, respectively.Finally, OLED with blue TADF material. Blue OLED with DMAC-DPS, which costs less than phosphorescence material and can achieve high performance, was made and optimized. Then using complementary color structure of WOLED, the light emitting layer contains blue TADF material DMAC-DPS and yellow fluorescence material HBT-pa with Stokes shift phenomenon. Diode shows the best performance with the structure of ITO/MoO3(1 nm)/mCP(40 nm)/DMAC-DPS:HBT-pa(1: 1)(30 nm)/DPEPO(10 nm)/Alq(40 nm)/LiF(1 nm)/Al. The maximum brightness is 1802.84 cd/m2, the maximum current efficiency is 5.18 cd/A, the maximum power efficiency is 3.58 lm/W, and the best CIE(Commission Internationale de L’Eclairage) is(0.28, 0.39).