Ta-Ya Chu

Stable inverted bottom-emitting organic electroluminescent devices with molecular doping and morphology improvement

Stable inverted bottom-emitting organic light-emitting diodes (IBOLEDs) have been investigated by inserting n-type Cs2O dopant between indium-tin oxide bottom cathode and Alq3, the combination of which not only improved the morphology of organic layer but enhanced the lifetime of the IBOLED. This n-type doped IBOLED achieved efficiencies of 5.2cd∕A and 2.0lm∕W at 20mA∕cm2. The 20% decay lifetime (t80) of Cs2O doped IBOLED is 270h which is about 1.7 times more stable than that of the conventional OLED (160h) and 2.5 times of Li doped IBOLED (104h).

Highly efficient and stable inverted bottom-emission organic light emitting devices

The authors report the development of highly efficient and stable C545T doped green fluorescent Alq3 inverted bottom-emission organic light emitting device (OLED), with a device configuration of ITO∕Mg∕Cs2O:Bphen∕Alq3∕C545T:Alq3∕NPB∕WO3∕Al, that achieved a maximum current efficiency of 23.7cd∕A and a power efficiency of 12.4lm∕W which are two times better than those of the conventional OLED. At a brightness level of 100cd∕m2, the device required driving current density only as low as 0.5mA∕cm2 at a driving voltage of only 5.0V and its half-lifetime T1∕2 in excess of 104000h.

Ultrathin Electron Injection Layer on Indium–Tin Oxide Bottom Cathode for Highly Efficient Inverted Organic Light-Emitting Diodes

We have fabricated a highly efficient inverted bottom-emission organic light-emitting diode (IBOLED) based on an indium–tin oxide (ITO) bottom cathode deposited with an ultrathin 1 nm layer of Mg to promote electron injection. The threshold voltage of this IBOLED with a structure of ITO/Mg/Alq3/NPB/WO3/Al was 4.2 V and an efficiencies of 4.66 cd/A and 1.51 lm/W were achieved at an operational voltage of 8.9 V and a brightness of 940 cd/m2. In comparison with an ITO/Alq3 bottom cathode composition, a reduction in drive voltage from 13.8 to 7.8 V in voltage was obtained at 1 mA/cm2. A charge-transfer dipole model is proposed to rationalize the enhanced electron injection.

Comparative study of single and multiemissive layers in inverted white organic light-emitting devices

The authors have fabricated and compared highly efficient inverted white organic light-emitting devices (WOLEDs) with a single emission layer (SEL) and with a multiemission layer (MEL). The efficiency levels of the WOLEDs with a SEL and a MEL achieved 13.0cd∕A, 10.6lm∕W and 11.3cd∕A, 7.3lm∕W, respectively. The projected half lifetime of a SEL device under an initial luminance of 400cd∕m2 is expected to be over 34000h, which is five times better than that of a MEL device of 6350h. The Commission International de l’Eclairage coordinates of a SEL device are not affected by aging.

29.2: Highly Efficient and Stable Inverted Bottom-Emission Organic Light Emitting Devices

We report the development of highly efficient and stable C-545T doped green fluorescent Alq inverted bottom-emission OLED (IBOLED) which achieved a maximum efficiency of 22.2 cd/A and 12.4 lm/W with an projected t1/2 of 30,000 h with L0 = 100 cd/m2. The DSA-Ph doped MADN sky blue fluorescent IBOLED device had a maximum efficiency of 12.7 cd/A and 7.6 lm/W. At a brightness level of 100 cd/m2, these green and blue IBOLED devices require drive current densities only as low as 0.5 and 0.9 mA/cm2, respectively.

P‐192: Highly Efficient Blue Organic Electroluminescent Devices

A series of highly efficient blue dopants based on the iminodibenzyl-substituted distyrylarylene (IDB-DSA) fluorescent dye using the concept of steric compression of a rigidized and over-sized ring have been designed and synthesized. When doped in the stable 2-(methyl)-9,10-di(2-naphthyl)anthracene (MADN), the seven-membered DSA (7-DSA-Ph) doped device achieved a luminance efficiency of 9.1 cd/A at 20 mA//cm2 with a CIEx,y color coordinate of (0.16, 0.28) and a maximum external quantum efficiency of 4.8%. When used in a 2-element WOLED system, the 7-DSA-Ph doped device achieved a luminance efficiency of 11.0 cd/A at 20 mA/cm2 with a CIEx,y color coordinate of (0.29, 0.36).