Polyelectrolyte-modified short microchannel for cation separation

Three alkali cations, potassium, sodium, and lithium, have been separated within 15 s in a 1 cm long polymer microchip. The separation microchannel is modified by a polycation, poly(allylammonium chloride), which makes the channel surfaces positively charged leading to a reversed electroosmotic flow (EOF) when compared to bare channels. Due to the decreased apparent mobility of the cations, the separation resolution is improved allowing the use of shorter channels.     

Efficient White Light Emitting Using an Electron Blocker in Non-Doped Type Organic Electroluminescent Devices

Non-doped type white organic electroluminescent (EL) devices using vacuum-deposited organic thin films of blue-emitting 4,4-bis(2,2 diphenylvinyl)-1,1-biphenyl (DPVBi) and yellow-emitting ultrathin 5,6,11,12-tetraphenylnaphthacene (rubrene) to generate white emission were fabricated. The two emitting layers are separated by an electron blocking layer of N,N-bis-(1-naphthyl)-N,N-diphenyl-1,1-biph-enyl-4,4-diamine (NPB). The thickness of the blocking layer determines the spectrum of the devices. In a device with 5 nm electron blocker of NPB, the CIE coordinates were well within the white region for voltage raging from 3 V to 14 V. The device has a maximum luminance of 7400 cd/m²(at current density of 830 mA/cm²) and maximum power efficiency of 1.67 lm/W at 5 V.     

基于单片机的数字化调光装置的设计与实现

介绍了一种光学仪器照明调光电路的创新设计。通过由Atmega8单片机微控制器产生的PWM信号来控制卤钨灯的亮度。照明调光电路具有电路简单,光强输出稳定,其亮度可数字化线性调节和具有记忆功能等特点,同时还可以通过计算机实现自动调光。     

Compact multimode interference coupler with tapered waveguide geometry

In this paper, a novel MMI coupler, based on general interference, with tapered waveguide geometry has been proposed for reduction of coupling length. The coupling characteristics and power imbalance of the proposed structure are compared with conventional MMI structures by using a mathematical model based on sinusoidal modes. It is seen that the beat length for tapered MMI coupler with angle of taper ∼1.05° is reduced by ∼24% of that of conventional MMI coupler and the coupling characteristics obtained with the mathematical model, match well with those obtained by more sophisticated BPM computer aided design software. The power imbalance for tapered 3 dB MMI coupler is more sensitive to the wavelength than that for conventional 3 dB MMI coupler and variation of power imbalance with fabrication tolerance for both the MMI coupler is almost same.     

Replication of microchannel structures in polymers using laser fabricated glass–ceramic stamp

A new microreplication process with photo-etchable glass–ceramic stamps and polymers is presented. This process has two main advantages: a rapid master fabrication with a laser process and a flexible replication process compared with conventional nano- or microreplication technique on polymers. Photo-etchable glass–ceramics are used for the master stamp. Micropatterns can be rapidly transferred with a laser direct writing process and the removal of the glass–ceramics can be efficiently achieved with a wet etching process. Therefore, microstructures with flat bottom surfaces and straight sidewall structures can be obtained, which is difficult in the laser direct writing process. A microstamping process of applying heat and pressure, also referred to as hot embossing lithography or microstamping, can replicate microstructures on polymer surfaces. In this work, the fabricated glass–ceramic stamps are used for the replication process and various replicated polymer microstructures are presented.     

单分子器件与电极间耦合界面对电子传输的影响

利用自恰tight-binding 理论，对由phenalenyl分子构成的全对称三电极纳米单分子器件的电子传导特性进行了理论研究. 通过改变电极与分子界面上的耦合，得出了分子与原子线电极间耦合强度变化对电子传输的影响. 结果显示电子通过phenalenyl分子器件的概率随着分子与电极的耦合强度变弱而减小. 当耦合强度变大时，不仅电子通过phenalenyl分子器件的概率变大，而且在较宽的能带内电子都可以通过phenalenyl分子. 所得结果还揭示出在特定的能区，对称三电极phenalenyl分子可以构成一个无源正负能量开关器件的新特性.     

Annealing effect on performance and morphology of photovoltaic devices based on poly(3‐hexylthiophene)‐b‐poly(ethylene oxide)

Novel block copolymers, poly(3‐hexylthiophene)‐b‐poly(ethylene oxide) (P3HT‐b‐PEO) were synthesized via Suzuki coupling reaction of P3HT and PEO homopolymers. The copolymers were characterized by NMR, gel permeation chromatography, differential scanning calorimeter, and UV–vis measurements. A series of devices based on the block copolymers with a fullerene derivative were evaluated after thermal or solvent annealing. The device using P3HT‐b‐PEO showed higher efficiency than using P3HT blend after thermal annealing. Phase‐separated structures in the thin films of block copolymer blends were investigated by atomic force microscopy to clarify the relationship between morphologies constructed by annealing and the device performance. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Organic light‐emitting device dark spot growth behavior analysis by diffusion reaction theory

Dark spot growth rate tracing experiments performed on an organic light‐emitting device show that moisture entering into the device is relatively properly fitted by Fick's diffusion equation in the substrate/indium tin oxide (ITO)/hole transport layer (HTL)/silver (Ag) structure. It is believed that the moisture is dissolved into the polymer layer, which results in a decrease in the diffusion coefficient in the device with the substrate/ITO/HTL/electroluminescent (EL) polymer/Ag structure. The diffusion and chemical reaction occurring in the cathode layer further decreases the diffusion coefficient in the device with the substrate/ITO/HTL/EL polymer/calcium/Ag structure. Useful parameters, such as diffusion and solubility constants, describing possible mechanisms happening during dark spot growth on organic light‐emitting diode devices are extracted. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1697–1703, 2001     

Selective area rare-earth doping of planar glass samples for monolithic integration of optically passive and active waveguides

Successful demonstration of selective area doping of planar glass samples for monolithic integration of optically passive and active devices on a single chip is presented. Salt solution of erbium was delivered onto pre-sintered germano-silicate samples via a syringe. The samples were then consolidated to form dense glass layers containing regions doped with rare earth. Erbium tri-chloride solution, 0.1 M, was used during the solution doping phase, with the resulting erbium atomic percentage ranging from more than 0.1-0.4%, increasing linearly with the number of drips applied.     

One-stage fabrication of sub-micron hydrophilic microchannels on PDMS

A sub-micron hydrophilic microchannel was fabricated on poly(dimethylsiloxane) (PDMS) in one step using vacuum ultraviolet light (VUV) lithography in vacuum. The topographies and properties of the irradiated PDMS surface were characterized and analyzed by atomic force microscopy (AFM), and the chemical composition changes on VUV-treated PDMS analyzed by X-ray photoelectron spectroscopy (XPS). The hydrophilic stability of irradiated PDMS surface was studied by static water contact angle. As demonstrated, the hydrophilicity on surface of PDMS microchannel can be kept for a longer term even three months after the treatment.