This research includes two parts as mentioned: (I) High efficiency red organic electroluminescent devices and (II) High efficiency white organic electroluminescent devices with broadband EL emission spectrum based on a single emitting layer. In part (I), we fabricated the high efficiency red organic electroluminescent devices incorporating 1,3,5-Tri(1-pyrenyl)benzene(TPB3) as the host material and 4-(dicyanomethylene)-2-tert-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) as the dopant. The highly efficient energy transfer arose as a result of (i) perfect overlap between the PL spectrum of TPB3 and the absorption spectrum of DCJTB and (ii) the high fluorescence quantum yield of TPB3. A device having the configuration ITO(1300 Å)/ NPB(650 Å)/ TPB3: 2% DCJTB(400 Å) / Alq3(300Å) / LiF(8Å) / Al(2000 Å) exhibited a maximum luminance at 13.5V of 70600 cd/m2, ca. four times higher than that of the device using Alq3 as the host material at the same potential. The device¡¦s current efficiency was 4.38 cd/A and its power efficiency was 2.12 lm/W at 20 mA/cm2;the maximum current and power efficiencies were 4.83 cd/A and 3.7 lm/W, respectively. The current and power efficiencies were greater than 4 cd/A and 1 lm/W, respectively, over the large range of potentials (3.5~13.5V) with good Commission Internationale de l¡¦Eclairage (CIE) coordinates of (0.63,0.37). These results indicate that searching for a suitable host material is a promising approach toward achieving high-efficiency red OLEDs. In part (II), we fabricated high-efficiency and color-stable broadband white organic electroluminescent devices based on a single emission layer, incorporating a green light-emitting host material which has large band gap and large Stoke¡¦s shift, doped with a red and a blue dye. TPB3 was used as the host material, and the red and blue light-emitting dyes were DCJTB and di(4-fluorophenyl)aminodi(styryl)biphenyl (DSB), respectively. A device having a simple configuration ITO(1300 Å) / NPB(650 Å) /TPB3: 10% DSB: 0.6% DCJTB(400 Å)/ Alq3(300Å) / LiF(8Å)/Al(2000 Å) exhibited a broadband white emission with a maximum luminance at 14.0 V of 81000 cd/m2, maximum current efficiency of 5.9 cd/A at 10.0 V, maximum power efficiency of 3.2 lm/W at 4.0 V. The Commission Internationale de l¡¦Eclairage (CIE) coordinates of (0.34,0.38) changed slightly over the large range of potentials (4~14.5 V). The high-efficiency¡Bhigh-bright and color-stable may be attributed to the high electroluminescence character of the host and the dopants, relatively high energy transfer from host to red dopant, and effective carrier-direct-recombination on a blue dopant, and the confinement of charge recombination zone in a single layer.

We have developed high-brightness white organic light-emitting diodes (OLEDs), which contain a tandem structure with two white electroluminescent (EL) units featuring a doping system comprised by a blue light-emitting host material [1,3,5-tris(1-pyrenyl)benzene (TPB3)] and a red light-emitting guest material[4-(dicyanomethylene) -2-tert-butyl -6-(1,1,7,7tetramethyljulolidyl-9-enyl)-4H-pyran(DCJTB)].In this study, we used Li doped[tris(8-hydroxyquinoline)aluminum (Alq3)] as the n-type connecting unit and MoO3 as the p-type connecting unit. We adjust the conceration of Li in the n-type connecting unit, try to find the best power efficiency.In the end,we find the 24% Li doped[tris(8-hydroxyquinoline)aluminum (Alq3)] as n-type connecting unit is the best conceration.A tandem device having the configuration ITO (140 nm)/NPB (65 nm)/ TPB3 (30 nm)¡GDCJTB (0.05%)/ Alq3(30 nm)/Alq3 (20 nm)¡GLi ( 24 %)/MoO3 (5 nm)/NPB (65 nm)/TPB3 (30 nm)¡GDCJTB (0.05%)/Alq3 (30 nm)/LiF (0.8 nm)/Al (200 nm) ,which exhibited a maximum luminance of 72100 cd/m2, a maximum power efficiency of 3.44 lm/W at 8V, a maximum external quantum efficiency of 4.72% at 20V.The Color Rendering Index(CRI) reached to 79,and the Commission Internationale DeL¡¦Eclairage chromaticity coordinates were (0.35, 0.35)at 26 V.We attribute the high-brightness of this system to the efficient white EL units and connenting layers.

It has been found that the results of 1,3,5-Tri(1-pyrenyl)benzene (TPB3) on the processing conditions of different depositon rates affect the morphology of thin films and the electroluminescent performance of the devices. At TPB3 deposition low rate, the average roughness of TPB3 thin film was much smoother comparing to high rate, the surface approached morphology and the wavelength peak was around 508nm. At TPB3 deposition high rate, the surface approached amorphous and the wavelength peak was around 476nm. Take advantage of varing deposition rates with different spectra to apply for colorful OLEDs. This research includes three parts as mentioned: (1) red organic light-emitting devices and (2) green organic light-emitting devices and (3) white organic light-emitting devices. In order to overlap perfectly between the host and dopant materials, we fabricated the red organic electroluminescent devices incorporating TPB3 at deposition low rate as the host material and 4-(dicyanomethylene )-2-tert-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) as red light-emitting dye and the green organic electroluminescent devices incorporating TPB3 at deposition high rate as the host material and 2,3,6,7-tetrahydro-1,1,7,7,-tetramethyl-1H,5H,11H-10(2- benzothiazolyl)quinolizine-[9,9a,1gh]coumarin (C545T) as green light-emitting dye, respectively. First, we deposited TPB3 at the lower rate of 0.1 Å/sec as the host material doped the red dopant, DCJTB, for making red OLEDs. The device: ITO(130nm)/NPB(65nm)/TPB3: 2% DCJTB(40nm)/Alq3(30nm) /LiF(0.8nm)/Al(200nm) exhibited a maximum luminance at 13.5V of 70600 cd/m2, ca. four times higher than that of the device using Alq3 as the host material at the same potential. The maximum current and power efficiencies were 4.83 cd/A and 3.7 lm/W, respectively. The current and power efficiencies were greater than 4 cd/A and 1 lm/W, respectively, over the large range of potentials (3.5~13.5V) with good Commission Internationale de l¡¦Eclairage (CIE) coordinates of (0.63,0.37). These results indicate that searching for a suitable host material is a promising approach toward achieving high-efficiency red OLEDs. The second, we deposited TPB3 at the higher rate of 3.0 Å/sec as the host material doped the green dopant C545T in order to overlap perfectly between them for spectra in green OLEDs. The device: ITO(130nm) /NPB(65nm) /TPB3: 1%C545T(40nm) /Alq3(30nm) /LiF(0.8nm) /Al(200nm) exhibited a maximum luminance at 11.5V of 166000 cd/m2, it¡¦s higher than that of the device using Alq3 as the host material at the same potential. The maximum current and power efficiencies were 10.0 cd/A and 6.67 lm/W, respectively. The current and power efficiencies were greater than 7.98 cd/A and 2.28 lm/W, respectively, over the large range of potentials (4.0~11.0V) with good Commission Internationale de l¡¦Eclairage (CIE) coordinates of (0.31, 0.61). These results indicate that TPB3 OLEDs are good than Alq3 OLEDs.. For TPB3 white OLEDs, we deposited TPB3 at the higher rate of 3.0 Å/sec as the host material doped the red dopant DCJTB in order to make high color purity white OLEDs. The device: ITO(130nm) /NPB(65nm) /TPB3: 0.05%DCJTB(40nm) /Alq3(30nm) /LiF(0.8nm) /Al(200nm) exhibited a maximum luminance at 11.5V of 55690 cd/m2, the maximum current and power efficiencies were 4.57 cd/A and 3.01 lm/W, respectively. The current and power efficiencies were greater than 3 cd/A and 0.91 lm/W, respectively, over the large range of potentials (3.5~11.5V) with good Commission Internationale de l¡¦Eclairage (CIE) coordinates of (0.34 , 0.34)~(0.33 , 0.33). These results indicate that TPB3 white OLEDs have good luminance and color purity.

We have developed high-efficiency blue organic light-emitting devices incorporate 1,3,5-Tri(1-pyrenyl)benzene(TPB3) as emitting layer and 4,7-diphenyl-1,10-phenanthroline(BPhen) as the electron transporting layer, which has a large Highest Occupied Molecular Orbital energy level and has good electron mobility. A device having the configuration : ITO(140 nm)/NPB(65 nm)/(TPB3 40nm)/BPhen(30 nm)/LiF(0.8 nm)/Al(200 nm) exhibited a maximum luminance at 9.5V of 29940 cd/m2, The maximum current and power efficiencies were 3.85 cd/A and 2.38 lm/W, respectively. The current and power efficiencies were greater than 3cd/A and 1.1 lm/W respectively, Over a large range of potentials (3.5~10.0V) with good Commission Internationale de l¡¦Eclairage (CIE) coordinates of (0.17, 0.22). These results indicate that TPB3 is good blue-emitting material for OLED applications. The photophysical and chemical properties of TPB3 have also been studied in this research.