Hou Jing-Ying

High-Efficiency White Organic Light-Emitting Devices Based on Multiple Quantum-Well Structure

We report the white organic-light devices (WOLEDs) employing a multiple quantum-well (MQW) structure, which consist of alternate layers of 4,48-bis(2,28-diphenylvinyl)-1,18-biphenyl (DPVBi) and (DPVBi:rubrene) as the potential barrier and the potential well, respectively. The results demonstrate that the MQW structure can prominently increase the performance of WOLEDs; the double quantum well device exhibits the efficiency up to 5.4 cd/A, and yields a peak luminance of 14206 cd/m2. It is also interesting to find that the MQW structure can enhance the colour stability of WOLEDs at different voltages.

High-Efficient Organic Light-Emitting Diodes Using Indium Tin Oxide Treated by KMnO4 Solution as Anode

High-efficient organic light-emitting diodes (OLEDs) with indium-tin-oxide (ITO) anode treated by KMnO4 solution are demonstrated. The performance of the OLEDs depends on the concentration of KMnO4 solution and time of ultrasonic treatment. The OLED whose ITO anode was treated by ultrasonic in KMnO4 solution with concentration of 50 mg/L for 15 min displays the best performance. It has higher electroluminescent brightness and lower turn-on voltage than those of traditional devices. In particular, its efficiency can be increased by approximately 40%. The surfaces of the ITO anode with and without treating are analysed by scanning electron microscopy.

Flexible Blue Light Emitting Diodes Made from Dye Doped Poly(N-Vinylcarbazole) with Multilayer Structure

Flexible blue light emitting diodes (LEDs) were fabricated by using poly(N-vinylcarbazole) (PVK) doped with high fluorescence dye, 1, 1, 4, 4-tetraphenyl-1,3-butadiene (TPB), as a emitter layer, a layer of tris(8-quinolinolato)aluminum (III) (Alq3) as an electron-transporting layer, and a layer of 2-(4-biphenylyl)-5-(4-tertbutypheny)-1-3,4-oxadiazole (PBD) as hole-blocking layer; a cell structure of flexible substrate/indium-tin-oxide /PVK:TPB/PBD/Alq3/Al was employed. In this cell structure, carrier injection from the electrodes to the doped PVK layer and concomitant electroluminescence from doped PVK were observed at room temperature with dc bias voltage of 4 V. Blue emission peaks at about 465 nm. This kind of LED is about 200 ?m thick and can be curled or bent repeatedly at sharp angles without failure.

Blue Electroluminescent Diodes Utilizing Blend of Poly (2, 5-Dibutoxyphenylene) in Poly (N-Vinylcarbazole)

Blue emission from polymer blends composed of poly (2,5-dibutoxyphenyiene) (PPP) in a matrix polymer poly (N-vinylcarbazole) (PVK) is reported. The light-emitting layer can be fabricated by spin-coating of PPP-PVK blend solution without subsequent processing or heat treatment. A cell structure of glass substrate /indium-tin-oxide /PPP-PVK blend/aluminum is employed. Blue light emission with a peak position at 448 nm occurs at a bias of about 8 V.

Top-Emitting Organic Light-Emitting Devices Based on Silicon Substrate with High Luminance and Low Turn-on Voltage

We have fabricated a top-emitting organic light-emitting device on silicon substrate with high yellow luminance based on 5,6,11,12-tetraphenylnaphthacene sub-monolayer. It consists of a thin layer of highly conductive silver as the semitransparent cathode and surfaced-modified Ag as the anode. The device turns on at 3 V with the luminance of 8.4 cd/m2. The maximum current efficiency is 1.3 cd/A at 6 V and the luminance reaches 14790 cd/m2 at 14 V. The performance of the device is excellent in top-emitting organic light-emitting devices according to our knowledge.

Improved Performances for Organic Light-Emitting Diodes Based on Al2O3-Treated Indium?Tin Oxide Anode

Improved performances are obtained in organic light-emitting diodes (OLEDs) based on the indium–tin oxide (ITO) anode processed with ultrasonic in Al2O3 polishing solution. By optimizing the Al2O3 granularity to 0.6 μm and the ultrasonic time to 10 min, smoother ITO surfaces are acquired, which lead to the enhanced hole injection, and furthermore, to improving the performance of OLEDs. Compared with the control device without any treatment, the drive voltage of treatment device falls from 9 V to 6 V at 100 cd/m2, the luminance is over three times that of the control device, reaching 25880 cd/m2 at 15 V, and the luminous efficiency is 3.82 cd/A.