High-refractive-index capping layer improves top-light-emitting device performance.

The performance of top-emitting organic light-emitting devices (TEOLEDs) was improved with capping layers having high refractive indices. The TEOLED electroluminescence was examined with different capping materials on the same device structure. The luminance and power efficiency in the forward direction was improved significantly by using a high-refractive-index capping layer.

Influence of carrier-injection efficiency on modulation rate of organic light source.

We have investigated the relationship between the energy levels of an emissive layer and the modulation rate of organic light-emitting diodes (OLEDs) based on a distyrylbenzene derivative, 1,4-bis[2-[4-[N,N-di(p-tolyl)amino]phenyl]vinyl]benzene (DSB). By utilizing DSB as an emitting material, a high modulation rate can be realized because of the short fluorescence lifetime of 0.2 ns of DSB. Furthermore, we also found that an energy gap between an emissive layer and an adjacent organic layer is an important parameter to improve modulation rate. DSB-doped 4,4-bis(2,2-ditolylvinyl)biphenyl is the best combination of all the organic materials used in this study, and the fastest cutoff frequency of 10 MHz has been achieved for the OLED in spite of the large emitting area of 1 mm(2).

Transient response of blue organic electroluminescence devices with short fluorescence lifetime of substituted phenyl/vinyl compound as an emissive layer.

We have demonstrated a short fluorescence lifetime of the substituted phenyl/vinyl compound, 1,4-bis[2-[4-[N,N-di(p-tolyl)amino]phenyl]vinyl]benzene (DSB). The fluorescence lifetime of the 0.5 mol.% DSB-doped 4,4'-bis(9-carbazolyl)biphenyl film is 1.2 ns, which is desirable for organic light-emitting diode (OLED) light sources for optical interconnect applications. We have also examined frequency dependences on the electroluminescence (EL) intensity of the OLED and the photoluminescence (PL) intensity of the DSB film. The -3 dB cutoff frequency of the EL intensity is about 3 MHz for the optimized device, and the -3dB cutoff frequency of the PL intensity is about 160 MHz for the optically pumping DSB film.

A photoluminescent six-coordinated zinc(II) complex with hydroxides as axial ligands, [Zn(Hhpa)2(OH)2] (Hhpa = 3-hydroxypicolinamide).

A highly luminescent zinc(II) complex has been prepared using 3-hydroxypicolinamide; it has a six-coordinated octahedral structure with hydroxides as axial ligands in solution.

Organic solid laser pumped by an organic light-emitting diode.

We have proposed what we believe is a novel organic device pumped by an organic light-emitting diode to avoid a strong charge-induced absorption and nonradiative loss in an electrically pumped organic laser. An organic light-emitting diode was fabricated on the transparent anode substrate with a microcavity structure and driven under intense pulse voltages, and an organic film with a low threshold of amplified spontaneous emission was spin-coated on the opposite side of the substrate. Edge emission, spectral from the film, has been measured under the pulse voltages. The optical characteristics of organic films under an Nd3+: YAG laser have also been studied.