Meng-Huan Ho

Highly efficient deep blue organic electroluminescent device based on 1-methyl-9,10-di(1-naphthyl)anthracene

The author have developed 2-methyl-9,10-di(1-naphthyl)anthracene (α,α-MADN) as an effective wide band gap host material for Forster energy transfer to the unsymmetrical mono(styryl)amine deep blue fluorescent dopant (BD-1). This guest/host emitting system, at the optimal doping concentration of 3%, can also increase the probability of carrier recombination near the hole-transport/emitting layer interface for the blue organic light emitting device which produces electroluminescence efficiencies of 3.3cd∕A and 1.3lm∕W and a deep blue CIEx,y color coordinates of (0.15, 0.13) that are 50% better than those of the traditional β,β-isomeric host (MADN) with the same dopant.

Highly efficient p-i-n white organic light emitting devices with tandem structure

Highly efficient tandem p-i-n white organic light emitting devices have been fabricated. Utilizing an optical transparent bilayer with doped organic p-n junction that consists of 4,7-diphenyl-1,10-phenanthroline: 2% cesium carbonate (Cs2CO3)∕N,N′-bis(1-naphthyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine: 50% v/v tungsten oxide (WO3) as the connecting layer, the tandem p-i-n white device achieved an electroluminescence efficiency of 23.9cd∕A and a power efficiency of 7.8lm∕W at 20mA∕cm2 with a Commission Internationale de l’Eclairage coordinates of (0.30, 0.43). The electroluminescent color of this tandem p-i-n white organic light-emitting diode device will not change significantly with respect to drive current variation and forward viewing angle.

Efficient deep blue emitters for organic electroluminescent devices

Highly efficient deep blue organic light emitting devices have been fabricated with a 4-(styryl)biphenyl-core based fluorescent dopant (SK-1) in the wide band gap 2-methyl-9,10-di(1-naphthyl)anthracene (α,α-MADN) host system which achieved an electroluminescence efficiency of 5.0cd∕A and an external quantum efficiency of 4.2% at 20mA∕cm2 with a saturated blue Commission Internationale de l’Eclairage coordinates of (0.15, 0.14) and a half-decay lifetime of 8000h at an initial brightness of 100cd∕m2. The current efficiency and electroluminescent color of SK-1 doped devices have been shown to be essentially immune to drive current density.

Study of efficient and stable organic light-emitting diodes with 2-methyl-9,10-di(2-naphthyl)anthracene as hole-transport material by admittance spectroscopy

An organic light-emitting device with enhanced efficiency sby employing 2-methyl-9,10-di(2-naphthyl)anthracene (MADN) as hole-transport material (HTM) has been developed. The admittance spectroscopy studies indicate that using MADN as HTM can reduce the amount of hole carriers injected into the device leading to a well-balanced carrier recombination. The green fluorescent 10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-benzo[l]pyrano-[6,7,8-ij]quinolizin-11-one doped tris(8-quinolinolato)aluminum device achieved a current efficiency of 21.8 cd/A and a power efficiency of 10.4 lm/W at 20u2002mA/cm2 that are 65% higher than those of the control device. The green-doped device also achieved a long half-decay lifetime of 22u2009000u2002h at an initial brightness of 500u2002cd/m2.

Study of electric characteristics and diffusion effects of 2-methyl-9,10-di(2-naphthyl)anthracene doped with cesium fluoride by admittance spectroscopy

In this work, the admittance spectroscopy studies show that doping cesium fluoride (CsF) into 2-methyl-9,10-di(2-naphthyl)anthracene (MADN) can greatly decrease the resistance of MADN and raises the Fermi level from deep level to only 0.1 eV below the lowest unoccupied molecular orbital, resulting in enhancing the electron injection. In addition, the diffusion width of CsF from doped MADN layer into tris(8-quinolinolato)aluminium is clearly observed by capacitance-frequency measurement and is about 9.4 nm. Moreover, the diffusion width is significant to be affected by external thermal.

Highly efficient and stable white light organic light-emitting devices

A highly efficient two-element white light organic light-emitting device with a sky blue dopant BUBD-1 and a yellow dopant TBRb was fabricated. The device achieved an electroluminescence efficiency of 17.1cd∕A and 7.9lm∕W at 20mA∕cm2. From 112 to 32u2009010 nits, the CIEx,y coordinates variation was Δ(x,y)<±(0.01,0.01), which is superior to common white light organic light-emitting devices (OLEDs) that tend to change color with drive conditions. Moreover, the device reached a half-decay t1∕2 lifetime over 40000h at an initial luminance of 300cd∕m2. This result is among the best records of fluorescent white light OLEDs.

64.2: Highly Efficient Deep Blue Electroluminescent Devices

A new deep blue dopant (SK-1) based on “linked” stilbene moiety has been designed and synthesized. When doped in the stable blue host material, 2-methyl-9,10-di(1-naphthyl)anthracene (α,α-MADN), the SK-1 doped blue device achieved a luminance efficiency of 5.0 cd/A with corresponding CIEx,y of (0.14, 0.14) at 20 mA/cm2 and an external quantum efficiency of 4.2%. The performance of SK-1 doped device performance under high/low drive current density remains stable for the needs of full color OLED application.