Abstract. We fabricated highly efficient blue organic light-emitting diodes (OLEDs) by designing differing emitting layer structures with fluorescent host and dopant materials of 4,4-bis (2,2-diphenylyinyl)-1,10-biphenyl and 9,10-bis (2-naphthyl) anthracene as host materials and 4,4'-bis (9-ethyl-3-carbazovinylene)-1,1'biphenyl (BCzVBi) as a dopant material to demonstrate electrical and optical improvements. Best enhancement in luminance and luminous efficiency were achieved by a quantum well structure in device F with 8668 cd∕m 2 at 8 V and 5.16 cd∕A at 103.20 mA∕cm 2 , respectively. Among the blue OLED devices doped by BCzVBi, device B emits the deepest blue emission with Commission Internationale de l'É clairage coordinates of (0.157, 0.117) at 8 V. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

We analyzed the performance of multi-emissive white phosphorescent organic light-emitting diodes (PHOLEDs) in relation to various red emitting sites of hole and electron transport layers (HTL and ETL). The shift of the recombination zone producing stable white emission in PHOLEDs was utilized as luminance was increased with red emission in its electron transport layer. Multi-emissive white PHOLEDs including the red light emitting electron transport layer yielded maximum external quantum efficiency of 17.4% with CIE color coordinates (−0.030, +0.001) shifting only from 1000 to 10 000 cd/m2. Additionally, we observed a reduction of energy loss in the white PHOLED via Ir(piq)3 as phosphorescent red dopant in electron transport layer.

The electroluminescent characteristics of blue organic light-emitting diodes(BOLEDs) were fabricated with single emitting layer using host-dopant system and doped charge carrier transport layers. The structure of the high efficiency BOLED device was; NPB(600Å)/NPB:BCzVBi-7%(100Å)/ADN:BCzVBi-7%(300Å)/BAlq:BCzVBi-7%(100Å)/BAlq(200Å)/Liq(20Å)/Al(1200Å) to optimize probability of exciton generation by doping BCzVBi in emitting layer and hole/electron transport layers(HTL/ETL) as well. Luminance and luminous efficiency of BOLED doped BCzVBi in EML and HTL/ETL improved from 10090 cd/m2 at 9.5V and 6.44 cd/A at 4.0V to 13190 cd/m2 at 9.5V and 7.64 cd/A at 4.0V about 30% and 18%, respectively, with CIE coordinates of (0.14, 0.17) comparing to BOLED doped BCzVBi in EML only

In this Letter, blue phosphorescence organic light-emitting diodes (PHOLEDs) employ structures for electron and/or hole confinement; 1,3,5-tris(N-phenylbenzimiazole-2-yl)benzene is used as a hole confinement layer and tris-(phenylpyrazole)iridium [IrðppzÞ 3 ] is utilized for an electron confinement layer (ECL). The electrical and optical properties of the fabricated blue PHOLEDs with various carrier-confinement structures are analyzed. Structures with a large energy offset between the carrier confinement and emitting layers enhance the charge-carrier balance in the emitting region, resulting from the effective carrier confinement. The maximum external quantum efficiency of the blue PHOLEDs with the double-ECLs is 24.02% at 1500 cd∕m 2 and its luminous efficiency is 43.76 cd∕A, which is 70.47% improved compared to the device without a carrier-confinement layer.

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