Surface Directed Phase Separation of Semiconductor Ferroelectric Polymer Blends and their Use in Non‐Volatile Memories

The polymer phase separation of P(VDF‐TrFE):F8BT blends is studied in detail. Its morphology is key to the operation and performance of memory diodes. In this study, it is demonstrated that it is possible to direct the semiconducting domains of a phase‐separating mixture of P(VDF‐TrFE) and F8BT in a thin film into a highly ordered 2D lattice by means of surface directed phase separation. Numerical simulation of the surface‐controlled de‐mixing process provides insight in the ability of the substrate pattern to direct the phase separation, and hence the regularity of the domain pattern in the final dry blend layer. By optimizing the ratio of the blend components, the number of electrically active semiconductor domains is maximized. Pattern replication on a cm‐scale is achieved, and improved functional device performance is demonstrated in the form of a 10‐fold increase of the ON‐current and a sixfold increase in current modulation. This approach therefore provides a simple and scalable means to higher density integration, the ultimate target being a single semiconducting domain per memory cell.     

SKF大型混合陶瓷深沟球轴承——风力发电机的可靠解决方案

早期的风力发电机轴承失效频繁发生,原因多种多样,在研究应用条件和调查轴承失效的基础上,基本确认了造成轴承失效的根本原因：双馈感应发电机变频驱动所导致的轴承过电流和相应的电腐蚀及润滑、磨损等。对风力发电机轴承早期失效的根本原因进行论述,同时介绍了SKF最新大型混合陶瓷深沟球轴承在减小轴承失效、增加运行可靠性方面的优势及其在风力发电机应用中的解决方案。     

An in vivo confocal Raman study of the delivery of trans retinol to the skin

The purpose of this study is to monitor in vivo the delivery of trans-retinol into human skin. Delivery to real systems, such as skin, can be extremely difficult to execute and is problematic to confirm and measure. So far, methods for studying the delivery of compounds through the skin are mostly ex vivo and so inherently influence the skin and may not translate directly to the in vivo situation. Raman spectroscopy is uniquely placed to be able to measure biological processes in vivo, and this paper shows that the trans-retinol penetration into the skin can successfully be measured in vivo using this technique. This study measured the volar forearm of volunteers treated with 0.3% trans-retinol in propylene glycol (PG)/ethanol and 0.3% trans-retinol in caprylic/capric acid triglyceride (MYRITOL318), an oil found in skin creams. Solutions were applied and then confocal Raman depth profiles were obtained of the stratum corneum (SC) and into the viable epidermis (VE) up to 10 hours after treatment. Remarkable differences between a penetrating and a nonpenetrating solution can clearly be observed. Treating with trans-retinol in PG/ethanol results in trans-retinol penetrating through the SC and into the VE. Its penetration was also observed to be highly correlated with the depth of penetration of the PG, which is well known as an efficient penetration enhancer. In contrast, while treating with trans-retinol in MYRITOL318, trans-retinol hardly penetrates at all. For the first time, the penetration of trans-retinol has been monitored directly after application of solutions, in vivo without skin excision. Here, the effect of two different solutions on the delivery of trans-retinol into the skin was measured very effectively in vivo by Raman spectroscopy.     

Programmable polymer light emitting transistors with ferroelectric polarization-enhanced channel current and light emission

We present a voltage programmable polymer light emitting field-effect transistor (LEFET), consisting of a green emitting polymer (F8BT), and a ferroelectric polymer, P(VDF-TrFE), as the gate dielectric. We show by both experimental observations and numerical modeling that, when the ferroelectric gate dielectric is polarized in opposite directions at the drain and source sides of the channel, respectively, both electron and hole currents are enhanced, resulting in more charge recombination and ～10 times higher light emission in a ferroelectric LEFET, compared to the device with non-ferroelectric gate. As a result of the ferroelectric poling, our ferroelectric LEFETs exhibit repeated programmability in light emission, and an external quantum efficiency (EQE) of up to 1.06%. Numerical modeling reveals that the remnant polarization charge of the ferroelectric layer tends to ‘pin’ the position of the recombination zone, paving the way to integrate specific optical out-coupling structures in the channel of these devices to further increase the brightness.     

X-ray imager using solution processed organic transistor arrays and bulk heterojunction photodiodes on thin,flexible plastic substrate

We describe the fabrication and characterization of large-area active-matrix X-ray/photodetector array of high quality using organic photodiodes and organic transistors. All layers with the exception of the electrodes are solution processed. Because it is processed on a very thin plastic substrate of 25 μm thickness, the photodetector is only 100 μm thick. When combined with an 300-μm-thick X-ray scintillator, this gives a thin, low-weight and shatterproof X-ray detector of ca. 400 μm thickness. We demonstrate X-ray imaging under conditions that are used in medical applications.     

Ferroelectric transistor memory arrays on flexible foils

In this paper, we successfully fabricated and operated passive matrix P(VDF–TrFE) transistor arrays, i.e. memory arrays in which no pass-transistors or other additional electronic components are used. Because of the smaller cell, a higher integration density is possible. We demonstrate arrays up to a size of 16 × 16, processed on thin (25 μm) poly(ethylene naphthalate) substrates, using Indium–Gallium–Zinc–Oxide (IGZO) as the semiconductor and 200 nm-thick P(VDF–TrFE) as a ferroelectric gate dielectric. The memory transistors have remnant current modulations of ～10⁵ with a retention time of more than 12 days. They can be switched in less than 1 μs at operating voltages of 25 V. Switching speed is strongly decreased with decreasing voltage: at ～10 V the transistors do not switch within 10 s. This difference in switching speed of more than 4 orders in magnitude when changing the electric field by a factor of only 2.5 makes these memories robust towards disturb voltages, and forms the basis of integration of these transistors in passive matrix-addressable transistor arrays that contains only one (memory) transistor per cell. It is shown that with current technology and memory characteristics it is possible to scale up the array size in the future.     

风力发电机中轴承的过电流问题

介绍了异步电动机中寄生电流的起因和影响,同时指出了双馈发电机与异步电动机在这方面的区别。讨论了轴承的一般电气性能,并展示了轴承损伤内部机理的最新研究成果。     

Circuits and AMOLED display with self‐aligned a‐IGZO TFTs on polyimide foil

A process to make self‐aligned top‐gate amorphous indium‐gallium‐zinc‐oxide (a‐IGZO) thin‐film transistors (TFTs) on polyimide foil is presented. The source/drain (S/D) region's parasitic resistance reduced during the SiN interlayer deposition step. The sheet resistivity of S/D region after exposure to SiN interlayer deposition decreased to 1.5 kΩ/□. TFTs show field‐effect mobility of 12.0 cm²/(V.s), sub‐threshold slope of 0.5 V/decade, and current ratio (I_ON/OFF) of >10⁷. The threshold voltage shifts of the TFTs were 0.5 V in positive (+1.0 MV/cm) bias direction and 1.5 V in negative (?1.0 MV/cm) bias direction after extended stressing time of 10⁴ s. We achieve a stage‐delay of ~19.6 ns at V_DD = 20 V measured in a 41‐stage ring oscillator. A top‐emitting quarter‐quarter‐video‐graphics‐array active‐matrix organic light‐emitting diode display with 85 ppi (pixels per inch) resolution has been realized using only five lithographic mask steps. For operation at 6 V supply voltage (V_DD), the brightness of the display exceeds 150 cd/m².