Blue organic light-emitting devices with an oxadiazole-containing emitting layer exhibiting excited state intramolecular proton transfer

We report a blue organic light-emitting device having an emissive layer of 2-(2-hydroxyphenyl)-5-phenyl-1,3,4-oxadiazole (HOXD), that exhibits excited state intramolecular proton transfer (ESIPT). The device had a luminance efficiency of 0.8 cd/A and a maximum brightness of 870 cd/m(2). Electroluminescence spectra revealed a dominating peak at 450 nm and two additional peaks at 480 and 515 nm with a full width at half maximum of 50 nm. Our studies indicate that some EL may originate from the triplet excitation state of the enol form of HOXD.

Synthesis and properties of alternating copolymers containing PPV and hole-transporting units for light-emitting devices

A series of alternating copolymers containing triphenylamine (TPA) moieties and oligomeric PPV segments in the main chain have been synthesized by Wittig condensation. The resulting polymers exhibit good thermal stability with decomposition temperatures (Tds) above 305 degreesC under nitrogen at 10 degreesC/min, and high glass transition temperatures (Tgs). They show intense photoluminescence in solution and film. The single-layer electroluminescent device using TAA-PV1 as emissive layer emits green light at 522nm with a turn-on voltage of 6V and maximum brightness of about 200cd/m(2) at 20V.

Effects of the morphologies and structures of light-emitting layers on the performance of organic electroluminescent devices

Organic electroluminescent devices with a structure of ITO/ploy (9-vinylcarbazole)/tris (8-hydroxyquinoline) aluminum (Alq3)/Mg:Ag are fabricated at different substrate temperatures (77, 298, and 438 K) during Alq3 deposition. It is found that the surface morphologies of Alq3 thin films greatly affect the I-V characteristics of the devices by the contact area between metal cathode and light-emitting layer. There is an increase in the luminous efficiency of the devices in the order 77 K < 298 K < 438 K. We attribute this trend to different structures of Alq3 thin films. (C) 2001 American Institute of Physics.

Bright green organic electroluminescent devices based on a novel thermally stable terbium complex

A navel thermally stable terbium carboxylate complex, Tb(MTP)(3)(phen) (MTP=monotetradecyl phthalate, phen=1,10-phehanthroline), was synthesized and characterized. The device structure of glass substrate/indium-tin-oxide/poly(p-phenylenevinylene) (PPV)/poly (N-vinycarbazole) (PVK):Tb(MTP)(3)(phen): 1,3,4-oxadizole derivative (PBD)/tris(8-hydroxyquinoline) (Alq(3))/aluminum (Al) was employed to study the electroluminescent properties of Tb(MTP)(3)(phen). A green emission with extremely sharp spectral band of less than 10 nm at 544 nm peak wavelength was observed. A maximum luminance of 152 cd/m(2) and an external quantum efficiency of 0.017% were achieved at a drive voltage of 24 V. A possible mechanism of energy transfer based on the polymer doped with lanthanide organic complex was also proposed.

Bright red organic electroluminescent devices based on a soluble rare earth complex Eu(TTA)(3) Phen

An Electroluminescent device with PVK film doped with Eu(TTA)(3) Phen and PBD was fabricated. The device structure of glass substrate/indium-tin-oxide/PPV/PVK : Eu(TTA)3 Phen : PBD/Alq(3)/Al was employed. A sharply red electroluminescence with a maximum luminance of 56. 8 cd/m(2) at 48 V was achieved.

Electroluminescent devices based on monohexadecyl phthalate terbium

Electroluminescent devices with PVK film doped with monohexadecyl phthalate terbium and PBD were fabricated. The device structure of glass substrate/ITO/PPV/PVK:Tb(MHP)(3):PBD/Alq(3)/Al was employed. The emissive layer was formed by a spin-casting technique. The EL cells exhibited characteristic emission of terbium ions with a maximum luminance of 74 cd/m(2) at 18 V. (C) 1998 Elsevier Science S.A. All rights reserved.

Organic electroluminescent devices using rare earth complex Eu(DBM)(3) as an emitter

Eu3+ narrow band emitting EL device with PPV, Alq(3) as hole and electron transportation layers has been prepared. The emitting layer, which consists of PVK, Eu(DBM)(3) and PBD is formed by spin-casting method. A maximum luminance of 52cd.m(-2) is achieved from the device.

Bright red electroluminescent devices based on a soluble lanthanide complex Eu(DBM)(3)(phen)

Electroluminescent devices with PVK film doped with Eu(DBM)(3)(phen) and PBD were fabricated. The device structure of glass substrate/indium-tin-oxide/PPV/PVK:Eu(DBM)(3)-(phen):PBD/Alq(3)/Al was employed. The emissive layer was formed by spin-casting method. A sharply red electroluminescence with a maximum luminance of 114.4 cd/m(2) was achieved at 42 V.

Bright blue electroluminescent devices utilizing poly (N-vinylcarbazole) doped with fluorescent dye

Bright blue electroluminescent devices have been fabricated using poly (N-vinylcarbazole) (PVK) doped with perylene as the emissive layer, poly(p-phenylenevinylene) (PPV) as the hole-transporting layer, 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD), tris(8-hydroxyquinoline)aluminum (Alq(3)) as the electron-transporting layer, and Al as the cathode. A luminance of 700 cd/m(2) and a luminescent efficiency of 0.8% are achieved at a drive voltage of 36 V. In the experiment, it is found that the introduction of electron-transporting layer PBD has a great effect on the emissive color of the electroluminescent devices prepared by PVK doped with perylene. Yellow-green emission is observed from the device structure of glass substrate/indium-tin-oxide/PVK:perylene/Al. The possible emissive mechanisms are given. The effect of the transporting layer on the electroluminescence is also discussed. (C) 1997 Elsevier Science S.A.

Photoluminesence and electroluminescence of the blue emission of devices based on poly(p-phenylenevinylene) copolymers

Bright blue polymer light-emitting diodes have been fabricated by using the poly(p-phenylenevinylene)-based copolymers with 10 C long aliphatic chains as the electroluminescent layers, PBD in PMMA and Alq(3) as the electron-transporting layers, and aluminum as the cathode. The multilayer structure devices show 190 cd/m(2) light-emitting brightness at 460 nm, 15 V turn-on vol- tage. It is found that the intensities of photoluminescence and electroluminescence (EL) increase with increasing aliphatic chain length, the EL intensity and operation stability of these polymer light-emitting diodes can be improved by reasonable design of the structure.

Microfluidic devices for the analysis of apoptosis

Apoptosis is the outcome of a metabolic cascade that results in cell death in a controlled manner. Due to its important role in maintaining balance in organisms, in mechanisms of diseases, and tissue homeostasis, apoptosis is of great interest in the emerging fields of systems biology. Research into cell death regulation and efforts to model apoptosis processes have become powerful drivers for new technologies to acquire ever more comprehensive information from cells and cell populations. The microfluidic technology promises to integrate and miniaturize many bioanalytical processes, which offers an alternative platform for the analysis of apoptosis. This review aims to highlight the recent developments of microfluidic devices in measuring the hallmarks as well as the dynamic process of cellular apoptosis. The potential capability and an outlook of microfluidic devices for the study of apoptosis are addressed.

Exploring the relationship between impulsivity and decision-making on mobile devices.

Mobile devices offer a common platform for both leisure and work-related tasks but this has resulted in a blurred boundary between home and work. In this paper we explore the security implications of this blurred boundary, both for the worker and the employer. Mobile workers may not always make optimum security-related choices when ‘on the go’ and more impulsive individuals may be particularly affected as they are considered more vulnerable to distraction. In this study we used a task scenario, in which 104 users were asked to choose a wireless network when responding to work demands while out of the office. Eye-tracking data was obtained from a subsample of 40 of these participants in order to explore the effects of impulsivity on attention. Our results suggest that impulsive people are more frequent users of public devices and networks in their day-to-day interactions and are more likely to access their social networks on a regular basis. However they are also likely to make risky decisions when working on-the-go, processing fewer features before making those decisions. These results suggest that those with high impulsivity may make more use of the mobile Internet options for both work and private purposes but they also show attentional behavior patterns that suggest they make less considered security-sensitive decisions. The findings are discussed in terms of designs that might support enhanced deliberation, both in the moment and also in relation to longer term behaviors that would contribute to a better work-life balance.

Ambiguity-generating devices in linguistic verbal jokes

Unpublished paper, written in 1996.

SymbolDesign: A User-centered Method to Design Pen-based Interfaces and Extend the Functionality of Pointer Input Devices

A method called "SymbolDesign" is proposed that can be used to design user-centered interfaces for pen-based input devices. It can also extend the functionality of pointer input devices such as the traditional computer mouse or the Camera Mouse, a camera-based computer interface. Users can create their own interfaces by choosing single-stroke movement patterns that are convenient to draw with the selected input device and by mapping them to a desired set of commands. A pattern could be the trace of a moving finger detected with the Camera Mouse or a symbol drawn with an optical pen. The core of the SymbolDesign system is a dynamically created classifier, in the current implementation an artificial neural network. The architecture of the neural network automatically adjusts according to the complexity of the classification task. In experiments, subjects used the SymbolDesign method to design and test the interfaces they created, for example, to browse the web. The experiments demonstrated good recognition accuracy and responsiveness of the user interfaces. The method provided an easily-designed and easily-used computer input mechanism for people without physical limitations, and, with some modifications, has the potential to become a computer access tool for people with severe paralysis.