Polarized electroluminescence from oriented p-sexiphenyl vacuum-deposited film

Abstract

Oriented sexiphenyl (6P) film was prepared through epitaxial growth on rubbed substrates by vacuum deposition. Polarized absorption spectra demonstrated that the long axis of 6P molecule was highly oriented along the rubbing direction. Using the epitaxial growth film of 6P, we fabricated electroluminescent (EL) devices consisting of indium-tin-oxide anode, emissive layer of 6P, electron-transporting layer of an oxadiazole derivative, and MgAg alloy cathode. Owing to the orientation of 6P molecules, EL polarized in the rubbing direction was observed in the devices.

Ultrafast photogeneration mechanisms of triplet states inpara-hexaphenyl

“…Organic -conjugated molecules are very attractive materials for optoelectronic devices such as organic light-emitting diodes [1][2][3][4] ͑OLED's͒, light-emitting electrochemical cells, 5 photodiodes, and solar cells. 6 Among them, size-controlled oligomers can be regarded as model compounds for studying fundamental properties of electrons in longer chain polymers.…”

“…PHP can be considered as a model substance for phenylene-based materials 8 and is used to build stable blue-emitting OLED's. [2][3][4]9 Due to its well-defined conjugation length and chemical structure, PHP exhibits well-resolved photoinduced absorption ͑PA͒ features that can be assigned to polaron-, triplet-, and singlet-state absorption. This allows us to optically address the exciton dissociation and polaron recombination dynamics in a real device structure with femtosecond time resolution.…”

Semiconductor Nanorod Liquid Crystals and Their Assembly on a Substrate

“…For various applications such as polarized light emitting diodes 22,23,24 , large areas of alignment of nanorods on a substrate are required. Thus it is of considerable interest to learn more about how nanocrystal superlattices nucleate on a substrate and how the nucleation events may potentially be controlled.…”

Polarized Light-Emission from Photonic Organic Light-Emitting Devices

“…To date, almost all previous work carried out on organic EL emission has involved unpolarized EL emission. Nevertheless, a number of researchers have reported the results of experiments in which linearly polarized EL emissions have been observed [6][7][8][9][10][11][12][13][14][15][16][17]. This particular avenue of research has been considered to be important because polarized EL emission from OLEDs is of potential use in a range of applications, not just those limited to high-contrast OLED displays, but also in efficient backlight sources in liquid crystal (LC) displays, optical data storage, optical communication, and stereoscopic 3D imaging systems [17].…”

“…Most cases of linearly polarized EL emission have been achieved through the use of uniaxially oriented materials, such as LC polymers or oligomers, incorporated within emissive layers. Methods that are commonly used for the uniaxial alignment of such layers include the Langmuir-Blodgett technique [6], rubbing/shearing of the film surface [7,8], mechanical stretching of the film [9,10], orientation on pre-aligned substrates [11,12], precursor conversion on aligned substrates [13], epitaxial vapor deposition [14], and the friction-transfer process approach [15,16]. Although there have been a number of such efforts to achieve linearly polarized EL emission, the polarization ratio and the device performance (in terms of brightness and efficiency) reported are still insufficient for most applications.…”