White-light OLED devices play an important application in information display fields. Optical interference of the microcavity structure has an important effect on device performances. According to the design of the band structure, ITO/MoO3 composite films were used as the anode, and Mg : Ag (1%) composite films were prepared by coevaporation as the translucent cathode; CuPc was used as the hole injection layer and anode passivation layer, NPB as the hole transmission layer and yellow light main material, rubrene as yellow dopant material, ADN as blue light main material, DSA-Ph as blue dopant material, and TPBi and Alq3 as the electron transport layers. We realized the change of the microcavity structure by adjusting the thickness of each organic functional layer film and simulated and calculated the optimized thickness of each organic film layer and influence on OLED device performances using the SimOLED software system. The optimized OLED microdisplay structure is Si(CMOS)/ITO (35 nm)/MoO3 (2 nm)/CuPc (5 nm)/2-TNATA (20 nm)/NPB (10 nm)/NPB : rubrene (1.5%)ADN : DSA-Ph (5%) (25 nm)/TPBi (15 nm)/Alq3 (1.2 nm)/Mg (13 nm) : Ag (1%). The optimized OLED microdisplay was prepared by the vacuum coating system, and the photoelectric performances of the OLED device were characterized by a spectral testing system consisting of the Photo Research PR655 spectrometer and Keithley 2400 program-controlled power supply. The effect of the microcavity structure on OLED device performances was studied. The results show that the variation of the film thickness of each organic functional layer has an important effect on the performances of OLED microdisplay, such as brightness and color coordinate, and the OLED microdisplay reaches a higher brightness of 3342 cd/m2 under the normal working voltage at 5.0 V after the structure is optimized, with CIE coordinate (0.28, 0.37), which is closer to the energy point of standard white light.

Tris(8-hydroquinoline) aluminum (Alq3) plays an important role in the applications of green organic light-emitting diodes (OLEDs). In this paper, Alq3 nanofilms were prepared on glass substrates by physical vapor deposition system with different surface states. The structures and morphologies of Alq3 nanofilms were characterized by X-ray diffractometer and scanning electron microscope. Alq3 nanomaterials were used as the main luminescent material for green OLED devices. The structure of the green OLED is Mo/2-TNATA (20 nm)/NPB (10 nm)/Alq3 (25 nm):Ir(ppy) 3 (5%)/Bphen (10 nm)/LiF (5 nm)/ Mg:Ag (10%) (10 nm). The photoelectric properties of green OLED devices were characterized by the system of Photo Research PR655 spectrometer. The results show that the weak interactions among Alq3 molecules such as π-π bond interactions and van der Waals forces caused molecules self-assembling into nanospheres, nanospherical chains, nanowires, or nanotubes in physical vapor deposition system. Precise surface state control of Alq3 nanomaterials can be realized by controlling the deposition temperature, thus, to enhance properties for green OLED displays. It is found that among different morphologies, Alq3 nanotubes have been proved to be the best green OLED devices with the brightness of 11,490 cd/m 2 , CIE (3358, 0.6302) at 5 V, and the current efficiency is 20.24 cd/A.

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