Transition metal oxides on organic semiconductors

Transition metal oxides (TMOs) on organic semiconductors (OSs) structure has been widely used in inverted organic optoelectronic devices, including inverted organic light-emitting diodes (OLEDs) and inverted organic solar cells (OSCs), which can improve the stability of such devices as a result of improved protection of air sensitive cathode. However, most of these reports are focused on the anode modification effect of TMO and the nature of TMO-on-OS is not fully understood. Here we show that the OS on TMO forms a two-layer structure, where the interface mixing is minimized, while for TMO-on-OS, due to the obvious diffusion of TMO into the OS, a doping-layer structure is formed. This is evidenced by a series of optical and electrical studies. By studying the TMO diffusion depth in different OS, we found that this process is governed by the thermal property of the OS. The TMO tends to diffuse deeper into the OS with a lower evaporation temperature. It is shown that the TMO can diffuse more than 20 nm into the OS, depending on the thermal property of the OS. We also show that the TMO-on-OS structure can replace the commonly used OS with TMO doping structure, which is a big step toward in simplifying the fabrication process of the organic optoelectronic devices.     

An ergonomic study of visual optimization by light color managements

Light‐emitting diodes (LEDs) have the advantage of controllable light colors and provide the optimal lighting quality against various color attributes required in different environments. However, from the humanized design point of view, beside satisfying physical demands of people, it is also important to achieve satisfaction. With a good match between the LED lighting equipment and ambient colors, the space imagery that complies with psychological needs of human beings can be found. This is expected to become a new market direction for future lighting. In this study, the LED light source feature of adjustable correlated color temperature is used to match wall colors of typical commercial spaces and for the investigation and analysis of the impact of colors of light sources and environments on human beings. The measures of mental and subjective feelings of a group of people under various circumstances have also been investigated. Multivariate analysis of variance has been conducted on three color temperatures of light sources, six wall colors, and measures of five emotion adjectives, and the correlation between these three variables has been further investigated. © 2014 Wiley Periodicals, Inc. Col Res Appl, 41, 72–84, 2016     

Impact of extinction coefficient of phosphor on thermal load of color conversion elements of phosphor converted LEDs

Besides their direct impact on the respective correlated color temperature, the extinction coefficient and the quantum effi- ciency of the phosphor also have tremendous impact on the thermal load of the color conversion elements of phosphor converted LEDs under operation. Because of the low thermal conductivity of the silicone matrix in which the phosphor particles are typically embedded, the by far highest temperatures within the LED assembly are reached within the color conversion element. Based on a combined optical and thermal simulation procedure we show that in particular a larger value for the extinction coefficient might have a beneficial impact on the resulting thermal load.     

Small-scale portable photovoltaic-battery-LED systems with submersible LED units to replace kerosene-based artisanal fishing lamps for Sub-Saharan African lakes

A technical simulation and economic model was developed for a floating photovoltaic (PV)-battery system powering a submerged light emitting diode (LED) lighting system. The system was designed to provide around the equivalent of 1000 lumens (lm) of light of the existing light fishing technology (a floating pressurised kerosene light) for artisanal light fishers to use for 8 h per night on Lake Victoria and other lakes in the region (Tanganyika, Rukwa, Mweru, Kivu, etc.). The net present cost (NPC) of a technically appropriate PV-battery-LED system was calculated as US$280 over 5 years, five-times less than the existing solar-based technology, a PV-battery-compact fluorescent lamp (CFL) system, and around ten times less than the baseline pressurised kerosene-based technology over the five years. Fishers owning the new PV-battery-LED system outright will likely recoup their initial investment within a year relative to the cost of alternatives, although the upfront capital cost of the new system was higher than the pressurised kerosene and PV-battery-CFL, and found to be practically unaffordable to the subsistence fishers without microcredit. Nonetheless, the technical simulations found that the new system was also able to provide additional lighting services during the day and evening, with little (if any) electrical impact on the system when in use for light fishing during the small hours of moonless nights. This research also demonstrates that the high cost of operating pressurised kerosene lamps precludes them for use in other applications within the community, including in homes. This research suggests that facilitated local development of appropriate new light fishing technology configurations will require training of local individuals to sensitise fishing communities to the new technology, and sustain wider adoption of the more efficient, cost-effective, and safer alternative.     

Quantification of six bioactive compounds in Zhenqi Fuzheng preparation by high-performance liquid chromatography coupled with diode array detector and evaporative light scattering detector

A simple and accurate high-performance liquid chromatography (HPLC) coupled with diode array detector (DAD) and evaporative light scattering detector (ELSD) was established for the determination of six...     

Roughness prediction on laser polished surfaces

The paper presents a methodology to predict the surface topography on laser polished surfaces. The method is based on the thermal field prediction generated by the laser. The thermal field is obtained through the differential equation of heat transfer by conduction. The prediction of the resulting topography is based on the filtering of the spatial frequency spectrum of the initial topography which is obtained by FFT analysis. Once the temperature field is obtained, a critical frequency is calculated and a low-pass filter is applied to cut the frequencies higher than the critical one. The resulting surface is reconstructed using the remaining frequencies. The methodology has been tested on a DIN 1.2379 tool steel and the experimental validation shows a relatively good agreement between the predicted and measured values of mean roughness (R_a) and mean roughness depth (R_z), with errors lower than 15% in all the cases.     

DNA-CTMA/a-Si:H bio-hybrid photodiode: A light-sensitive photosensor

Recently, considerable interest have occurred in the development of an organic-inorganic-based bio-hybrid photodiodes (Bio-HPDs) with metal-free, eco-friendly, and cost-competitive features for light-sensitive devices. This paper reports a bio-inspired optical absorber material for the fabrication of Bio-HPDs using n-type hydrogenated amorphous silicon (a-Si:H) and a natural deoxyribonucleic acid (DNA)-cetyltrimethylammonium chloride (CTMA) biomaterial. a-Si:H is inexpensive and abundant, and DNA-CTMA is metal-free and eco-friendly. A DNA-CTMA coating on n-type a-Si:H leads to a chemically stable material with increased absorption and effective ties of dangling bonds and interface state density. Analysis results showed that the rectification ratio (RR) of the Bio-HPD is found to be 4 times higher than reference PD. This indicates that the effective RR is improved by the DNA-CTMA layer since it creates molecular charge interactions between DNA-CTMA layer and a-Si:H substrate. Moreover, Bio-HPD shows a light photosensitivity (I_photo/I_dark) of 474 with more reliable and has longer life time. In addition, the formation and feasible charge transport mechanisms are discussed. This biomaterial can be used for the development of commercially viable and environmentally safe large-scale Bio-HPDs applications.     

高效应用的增强型第4代CAL二极管

使用轴向寿命控制(CAl-controlled axial lifetime)技术,SEMIKRON将他的第4代续流二极管从1200V扩展到了650V和1700V电压等级。一种创新的终端结构提供了对于极端环境,如湿度影响的高稳定性。此外,这种终端结构使器件能够稳定地工作到175°C。增强型CAL4二极管还对低频及高频等级分别进行了优化,以便获得较好开关特性和较低损耗的最佳折衷。     

A review of heat pipe systems for heat recovery and renewable energy applications

Advancements into the computational studies have increased the development of heat pipe arrangements, displaying multiphase flow regimes and highlighting the broad scope of the respective technology for utilization in passive and active applications. The purpose of this review is to evaluate current heat pipe systems for heat recovery and renewable applications utility. Basic features and limitations are outlined and theoretical comparisons are drawn with respect to the operating temperature profiles for the reviewed industrial systems. Working fluids are compared on the basis of the figure of merit for the range of temperatures. The review established that standard tubular heat pipe systems present the largest operating temperature range in comparison to other systems and therefore offer viable potential for optimization and integration into renewable energy systems.