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This paper presents a new biophotonic application for large-area, high-resolution, flexible organic light-emitting diode (OLED) display technology currently used to manufacture low-cost color flexible displays on plastic substrates. The new concept uses a fully addressable high resolution flexible OLED pixel array on a thin, mechanically compliant biocompatible plastic substrate to selectively stimulate and/or silence small groups of neurons on either the cortical surface or, alternatively, within the deep brain. Optical measurements from a 455 nm blue flexible OLED test structure demonstrated the ability to emit 1 ${\hbox{mW/mm}}^{2}$ of instantaneous light intensity using a 13 V, 20 Hz pulse, which meets the minimum reported intensity at $\sim$ 450 nm to induce optical stimulation in genetically modified neural tissue. Biocompatibility was successfully demonstrated by the ability to grow human epithelial cells on the surface of a full TFT process flow plastic flexible display substrate. Additionally, a new active matrix array display architecture was designed to support pulsed mode OLED operation. These preliminary results demonstrate the initial viability of extending flexible plastic substrate OLED display technology to the development of large-area, high-resolution emissive active matrix arrays for chronic optogenetic applications.

How the application of commercial (thin film) flat panel display technology, used in the production of flexible displays and flexible digital X-ray detectors, can also be applied to reduce the manufacturing cost of wearable biomedical devices, as well as potentially improve their diagnostic functionality, is explored. As a technology platform to evaluate the presented new concept, a prototype photoplethysmograph biosensor using a flexible organic light-emitting diode display and pin photodiode (thin film) sensor technology for optical heart rate monitoring is developed.

The widely used motors in HEV(Hybrid Electric Vehicles) are IPMSM(Interior Permanent Magnet Synchronous Motor) which has no rotor heat, higher efficiency and advantageous in volume and weight comparing with other motors. For vector control of IPMSM, position information of rotor is required but Resolver is mainly used as the detecting sensor. However, the use of position sensors will reduce the system reliability of hybrid electric vehicles. In this paper, a way to control the motor by sensorless was proposed at the event of sensor failure. We also implemented IPMSM sensorless operation by the expanded EMF(Electro Motive Force) voltage way and harmonic voltage which is applying in the low speed area. And we proposed how to change with sensorless control by detecting the position sensors failure and verified it through experiments.

This paper presents the torque control algorithm of a permanent magnet synchronous motor(PMSM) for an electric scooter. The volume of the in-wheel type motor is restricted due to the complicated mechanical structure in wheel of an electric scooter, so the hall sensors instead of resolver and encoder for the rotor position sensors are installed. In this paper, the rotor speed and position are estimated from the speed estimator for vector control of a PMSM with hall sensors. The motor starts to rotate at standstill in BLDC mode with 120 degree conduction. After start up, the operating mode is changed to the vector control with maximum torque per ampere(MTPA) operation at low speeds and flux weakening control at high speeds. The performance of the proposed control algorithm is verified through the experiment in the electric scooter.

MDPS (motor driven power steering) systems have been widely used in vehicles due to their improved fuel efficiency and steering performance when compared to conventional hydraulic steering. However, the reduction of torque ripples and material cost are important issues. A low resolution position sensor for MDPS is one of the candidates for reducing the material costs. However, it may increases the torque ripple due to the current harmonics caused by low resolution encoder signals. In this paper, the torque ripple caused by the quantized rotor position of the low resolution encoder is analyzed. To reduce the torque ripples caused by the quantization of the encoder signals, the rotor position and the speed are estimated by measuring the frequency of the encoder signals. In addition, the compensating q-axis current is added to the current command so that the 6th order torque harmonic is attenuated. The reduction of torque ripples by applying the estimated rotor position and the compensated q-axis current is verified through experimental results.

A series of white polymer light-emitting devices has been fabricated by using a spiropolyfluorene (SF) blue polymer with an orange Ir complex as a blend system. A SF single polymer host and mixed co-host with CBP (4,4-N,N-dicarbazolebiphenyl) or PBD (2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole) are investigated to get high efficiency white OLEDs. A good color coordination of (0.34, 0.36) with a good current efficiency of 1.52 cd/A at 2% doped condition in a CBP mixed co-host system is reported.

We report efficiency increase and voltage reduction by bipolar host materials, 4,4′- N , N′ -dicarbazoleterpheyl and 4,4′- N , N′ -dicarbazolequaterpheyl, in green and red phosphorescent organic light-emitting diodes (PHOLEDs). These host materials are designed to have good electron transporting characteristics with narrow band-gap by adding more phenyl moieties in a 4,4′- N , N′ -dicarbazolebiphenyl (CBP) chemical structure. At a given constant luminance of 1000 cd/m 2 , power efficiency is enhanced at least by twenty percent compared to general CBP based green and red PHOLEDs.

We report a high efficiency red phosphorescent OLED (PHOLED) with organic bilayered structure. The structure of bilayered red PHOLEDs was ITO/ N,N″-di(naphthalene-1-yl)-N,N″-diphenyl-benzidine (NPB)/new host: Ir(piq)3/LiF/Al. A high current efficiency of 10.0 cd/A and a power efficiency of 7.8 lm/W at 500cd/m2 was demonstrated in this device. The operation driving voltage to reach 1000 cd/m2 was 4.5 V and CIE coordinate was (0.67, 033). This bilayered PHOLED fabricated by a new phosphorescent host material resulted about 3 times enhancement of power efficiency compared with that of a CBP based control device.

The electroluminescent characteristics of the host MEH–PPV and PVK polymeric light-emitting diodes with and without doping carbon nanotubes (CNTs) have been demonstrated. For MEH–PPV-based devices, maximum luminance of the pristine and CNTs-doped polymeric light-emitting diodes exhibit 3900 cd/m2 at 5.0 V and 3600 cd/m2 at 5.4 V. For PVK-based devices, maximum luminance of the pristine, 0.05% and 0.1% CNTs-doped polymeric light-emitting diodes exhibit 3600 cd/m2 at 6.2 V, 7600 cd/m2 at 8.2 V and 6800 cd/m2 at 9.1 V. The performance of polymeric light-emitting diodes in electroluminescence has been demonstrated by the improvement of doping carbon nanotubes in polymer matrix. This may be due to the chemical interaction bonding between carbon nanotubes and organic molecules in the polymer matrix and the variation of energy level in electronic structure.

We have fabricated white polymer light-emitting devices (WPLEDs) from RGB polymer blending systems using ITO/PEDOT:PSS/blended polymers/LiF/Al structure. The highest current efficiency reached 5.34 cd/A and the maximum brightness value of 27,000 cd/m2 at 11.4 V was obtained. As the green dopant concentration increased, the spectrum deviated from the white because of more energy transfer from host to guest. As a result, the 450 nm blue peak was reduced by increasing green dopant ratio. On the other hand, 600 nm red shoulder peaks were slightly increased at the same conditions. Therefore, red-orange and green electroluminescence emissions are promoted by excitation energy and charge transfer from the blue host polymer to the dopants.

Pb(ZrxTi1−x)O3 (PZT) ferroelectric thin films were prepared by metalorganic chemical vapor deposition (MOCVD) on Pt/Ti/SiO2/Si substrate. Very thin PZT films, which were deposited at a lower temperature and post-annealed at higher temperature for crystallization, were used as a seed layer. PZT films grown on the seed layer exhibited superior characteristics in the crystalline structure and electrical properties, compared to those deposited without seed layer. Depending on the deposition conditions of PZT seed layer, a wide variation of surface morphology and stoichiometry was found between samples, whereas chemical composition was found to be very similar.

Improvement of reliability, specially high endurance and retention characteristics, of PZT capacitors has been a main question for high density FeRAM development. Pt/IrO2 hybrid electrode has been suffered from the hydrogen degradation due to the strong catalytic function of Pt. Thus, IrO2 electrode can be a good candidate for the minimizing hydrogen related degradation. We have investigated the variation in ferroelectric properties such as fatigue, retention and hydrogen effect of PZT capacitors grown on the IrO2 electrodes in comparison with those grown on the Pt/IrO2 hybrid electroe

A cooperative local dimming (CLD) method that effectively controls the brightness of the backlight unit is proposed. This CLD method takes into account the brightness of neighbouring light sources to achieve a backlight brightness that should be minimally higher than the brightness required by the pixels on the screen. The proposed CLD method matches pixel brightness more accurately and saves more energy than conventional local dimming methods do, thereby improving the quality of images and energy efficiency.

A low temperature, 180 °C, amorphous Si (a-Si:H) process on bonded polyethylene naphthalate substrates is discussed and a 4.1-inch QVGA active matrix (AM) phosphorescent OLED display is demonstrated. The n-channel thin-film transistors (TFTs) exhibited saturation mobilities of 0.773 cm2/V-sec, layer to layer registration distortion less than 10ppm and low defectivity. The efficiency of the OLED display is 39 cd/A at 500 nits.

We present highly efficient red and green phosphorescent devices comprising only two organic layers. Novel host materials having good electron transporting and new narrow band-gap fluorescent characteristics lead to the fabrication of simplified high efficiency devices. The driving voltage value of 3.3 V to reach luminance of 1000 cd/m 2 is reported in simple bi-layer red and green phosphorescent OLEDs, respectively. The maximum current- and power-efficiency values of 38.30 cd/A and 46.60 lm/W are demonstrated in this green device. The current and power efficiencies of bi-layered red PHOLED are 9.38 cd/A and 11.72 lm/W. Results reveal a practical way to fabricate highly efficient truly bi-layer organic devices for trouble-free manufacturing processes.

With the aim of enhancing the electron injection of a polymer light-emitting diode (PLED), a supramolecular insulating nanolayer that reacts with the cathode (Ag) was inserted between the bottom cathode and the emitting material. The PLED threshold voltage (for 1cd∕m2) was found to decrease from 5.6to4.2V as a result of the introduction of the nanolayer. Synchrotron radiation photoelectron spectroscopy results show that inserting the supramolecular insulating nanolayer results in a decrease in the work function of about 0.7eV. This reduction lowers the electron injection barrier and produces an increase in the luminance.

We have developed a 2.2 inch top-emission AMOLED display on flexible metal foil with an inverted staggered TFT using P-SOG (phosphosilicate-based spin-on-glass) as a gate insulator. The gate insulator was planarized on flexible metal foil by spin coating. The p-channel poly-Si TFT on metal foil exhibited the field-effect mobility of 51.2 cm2/Vs, threshold voltage of −5.3V, and the gate voltage swing of 1.0 V/dec. Green AMOLED with 128×160 pixels was demonstrated with a LTPS AM backplane with 2 TFTs and 1 capacitor in a pixel.