Tris(8-Hydroxyquinoline) Aluminum/2-(4-Biphenylyl)-5-(4-Tertbutylphenyl)-1,3,3-Oxadiazole Organic Multiple Quantum Wells for Electroluminescent Devices

Organic multiple quantum wells(OMQWs) consisting of alternating layers of organic materials have been fabricated from tris(8-hydroxyquinoline) aluminum(Alq)and 2-(4-biphenylyl)-5-(4-tertbutylphenyl)-1,3,3-oxadiazole(PBD) by a multisource-type high-vacuum organic molecular deposition.From the small-angle X-ray diffraction patterns of Alq/PBD OMQWs,a periodically layered structure is confirmed through the entire stack.The Alq layer thickness in the OMQWs was varied from 1 nm to 4 nm.From the optical absorption,photoluminescence and electroluminescence measurements,it is found that the exciton energy shifts to higher energy with decreasing Alq layer thickness,The changes of the exciton energy could be interpreted as the confinement effects of exciton in the Alq thin layers.Narrowing of the emission spectrum has also been observed for the electroluminescent devices (ELDs) with the OMQWs structure at room temperature.

Hole Mobility in Poly (N-vinylcarbazole) Thin Film Based on Silicium

The mobilities of holes in thin,spin-casting films of poly( N -vinylcarbazole)(PVK) based on silicium are measured using a time-of-flight (TOF) technique.The drift of hole mobility is strongly dependent on the electric field and temperature.At room temperature and an electric field of 2×10 5 V·cm -1 ,the effective mobility of hole is 7.14×10 -6 cm 2·V -1 ·s -1 ,in a 200 nm thick sample.

Electron Mobility in Tris（8—Hydroxyquinolinolato）Aluminum Thin Film Based on Silicium^①②

We have measured the mobilities of electrons in thin,vapor-deposited films of tris(8-hydroxyquinolinolato)aluminum(Alq3)based on silicium using a time-of-flight(TOF)technique.The drift of electron mobility is strongly electric field and temperature dependent.At room temperature and an electric field of 2×10^5V·cm^-1,the effective mobility of electron is 1.0×10^-5cm^2·V^-1·s^-1 for 200nm thick sample.

Fabrication of Alq_3/PBD OMQW Structures and Its Photoluminescence Characteristics

Abstract: Organic multiple quantum well(OMQ) structures consisting of alternating layers of tris(8 - quinolinolato)aluminum( ff) (Alq3) and 2 - (4 - biphenylyl) -5 - (4 - ter - butylphenyl) -(1,3,3- oxadiazole) (PBD) have been fabricated by organic molecular beam deposition (OMBD). The individual layer thickness in the multilayer samples was varied from 6 nm to 20 nm. The multiple quantum well structures were determined by low angle X - ray diffraction, optical absorption and photolumi-nescence(PL). The PL spectra narrow and the emission energy has been observed to shift to higher energy compared with that in the monolayer structure, suggesting a quantum size effect.

Moiecuiar Doped Poiymer Light Emitting Diodes with Air—stabie Aluminum as Cathode

By using air-stable alumminum as cathode,molecular doped polymer (MDP)blue light emitting diodes(LEDs)were constructed.Poly(N-vinylcarbazole(PVK)doped with,1,1,4,4-tetrapheny 1-1,3-butadiens(TPB)was used as the light-emitting layer,a layer of 2-(4-biphenylyl)-5-(4-terbutypheny)1-3,4-oxadiazole(PBD) as hole-blocking,electron-transporting layer and a layer of tris(8-quinolinolate)-Aluminum(Alq3)film also worked as an electron-transporting layer.The device with structure of ITO/PVK;TPB/PBD/Alq3/Al was fabricated.Blue emis-sion began at about 4V,more than 1000 cd/m^2 was achieved at 14V.This is the lowest turn-on voltage for polymeric lgiht-emitting diodes(PLEDS)used air-stable elec-trodes.Such low-operating voltage,especially using air-stable aluminum as cathode,may be helpful for the devices to be used in commercially viable displays.