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排序方式: 共有2628条查询结果,搜索用时 15 毫秒
41.
Kazuki Yanome Takayuki Kiba Midori Kawamura Yoshio Abe Kyung Ho Kim Junichi Takayama Akihiro Murayama 《Journal of Electronic Materials》2017,46(7):3873-3879
We report the ellipsometric and photoluminescence (PL) properties of Indium zinc oxide (IZO) films, which were grown by radio frequency sputtering under Ar and O2 atmospheres. IZO films grown under an O2 atmosphere (IZO (O2)) showed enhanced PL properties when compared to the films grown under an Ar atmosphere (IZO (Ar)), particularly with respect to the band-edge emission. The enhancement of band-edge emission can be attributed to the reduction in the non-emissive defect states related to oxygen vacancies, which were repaired by sputtering under O2 atmosphere, whereas the PL enhancement in green region is probably due to the formation of the different types of defects under the excess oxygen environment. This was also supported by the results of time-resolved PL measurements, where the band-edge emission of IZO (Ar) showed rapid decay with a 50 ps lifetime, which indicates the dominance of the relaxation pathway to underlying defect states. In contrast, the PL decay profiles of IZO (O2) for band-edge and emissive defect states showed moderate decay with time-constants of 2.3 ns and 5.7 ns, respectively. The exciton relaxation dynamics were sensitive to the presence and its kinds of defect states, which were controlled by the growth conditions. 相似文献
42.
Na Yeon Kim Jihoon Kyhm Hyemi Han Soo Jin Kim Jongtae Ahn Do Kyung Hwang Ho Won Jang Byeong‐Kwon Ju Jung Ah Lim 《Advanced functional materials》2019,29(11)
Herein, a simple and facile strategy is described to obtain chiroptically active semiconductor thin films by blending of poly(3‐alkylthiophene)s, which are conventional achiral polymer semiconductors, and 1,1′‐binaphthyl (BN), a versatile chiral molecule. As expected, the intermolecular interaction between the two materials is important to extend the chirality of the binaphthyl molecules to the hybrid films. The controlled phase separation and crystallization of poly[3‐(6‐carboxyhexyl)thiophene‐2,5‐diyl] (P3CT) and binaphthyl hybrid films result in unique heterojunction bilayer thin‐film structures that consisted of BN microcrystals at the top and a P3CT/BN mixed layer at the bottom. Such heterojunction bilayer films exhibit significantly amplified chiroptical response with weak broadened tails, which is due to the enhanced crystallization of the chiral BN molecules and formation of heteroaggregates in the hybrid films. Based on the characterization of crystalline structure and photoluminescence analysis, it is found that new electronic energy states are formed in the conduction band region of P3CTs in the P3CT/BN heteroaggregates, which contribute to chirality transfer from BN to the hybrid films. As a proof of concept, a photodiode capable of distinguishably sensing the left‐ and right‐handed circularly polarized light is successfully fabricated by using the hybrid films with the heterojunction bilayer structure. 相似文献
43.
This paper presents the measurement of the nonlinear mechanical properties of polydimethylsiloxane (PDMS) elastomer based on the mixing ratio of base polymer to curing agent. Strip-type PDMS samples with different mixing ratios were prepared using a simple coating, curing, and cutting process. A cyclic uniaxial tension test with a fixed magnitude of applied strain and a single-pull-to-failure tension test were performed with a micro-tensile tester at room temperature.Our new finding is that when the PDMS is mixed with excessive curing agent, stress softening occurs and residual strain exists in cyclic tension tests when the magnitude of the applied strain increases. For the PDMS-05 samples, in which the mixing ratio of base polymer to curing agent was 5 to 1, there were large differences in the stresses for the same strain level under loading and unloading during the first cycle with a 100% fixed strain amplitude, but the softening effect of the stress in the PDMS dropped rapidly starting from the second cycle.Nonlinear mechanical Neo-Hookean, third-order Mooney, and second-order Ogden models of three different PDMS films were computed from the stress-strain data. The results showed that all models were preferable for the small strain region of PDMS compared with other models. In the nonlinear, large strain region, only the second-order Ogden model properly described the mechanical behavior of the PDMS, while the Neo-Hookean and third-order Mooney-Rivlin models were too stiff or flexible in the measurement range. The bulk modulus of PDMS increased with the amount of curing agent in it. Therefore, the second-order Ogden model is preferable for analyzing the PDMS structure over the entire measurement range. This could provide reasonable mechanical models of PDMS for rapid computational prototyping and for designing active and passive components from PDMS. 相似文献
44.
Heon-Bok Lee Hyun Jeong Yang Ju Hyung We Kukjoo Kim Kyung Cheol Choi Byung Jin Cho 《Journal of Electronic Materials》2011,40(5):615-619
A new process for fabricating a low-cost thermoelectric module using a screen-printing method has been developed. Thermoelectric
properties of screen-printed ZnSb films were investigated in an effort to develop a thermoelectric module with low cost per
watt. The screen-printed Zn
x
Sb1−x
films showed a low carrier concentration and high Seebeck coefficient when x was in the range of 0.5 to 0.57 and the annealing temperature was kept below 550°C. When the annealing temperature was higher
than 550°C, the carrier concentration of the Zn
x
Sb1−x
films reached that of a metal, leading to a decrease of the Seebeck coefficient. In the present experiment, the optimized
carrier concentration of screen-printed ZnSb was 7 × 1018/cm3. The output voltage and power density of the ZnSb film were 10 mV and 0.17 mW/cm2, respectively, at ΔT = 50 K. A thermoelectric module was produced using the proposed screen-printing approach with ZnSb and CoSb3 as p-type and n-type thermoelectric materials, respectively, and copper as the pad metal. 相似文献
45.
Yoo Seung Song Shin Kyung Lee Jeong Woo Lee Do Wook Kang Kyoung Wook Min 《ETRI Journal》2019,41(6):703-714
Many use cases have been presented on providing convenience and safety for vehicles employing wireless access in vehicular environments and long‐term evolution communication technologies. As the 70‐MHz bandwidth in the 5.9‐GHz band is allocated as an intelligent transportation system (ITS) service, there exists the issue that vehicular communication systems should not interfere with each other during their usage. Numerous studies have been conducted on adjacent interfering channels, but there is insufficient research on vehicular communication systems in the ITS band. In this paper, we analyze the interference channel performance between communication systems using distribution functions. Two types of scenarios comprising adjacent channel interference are defined. In each scenario, a combination of an aggressor and victim network is categorized into four test cases. The minimum requirements and conditions to meet a 10% packet error rate are analyzed in terms of outage probability, packet error rate, and throughput for different transmission rates. This paper presents an adjacent channel interference ratio and communication coverage to obtain a satisfactory performance. 相似文献
46.
47.
Soo Won Heo Eui Jin Lee Kwan Wook Song Jang Yong Lee Doo Kyung Moon 《Organic Electronics》2013,14(8):1931-1938
In this study, polymer solar cells (PSCs) doped with Au nanoparticles (Au NPs) were successfully fabricated to maximize the photon-harvesting properties on the photoactive layer. In addition, a conductivity-enhanced hybrid buffer layer was introduced to improve the photon absorption properties and effectively separate the generated charges by adding Au NPs and dimethylsulfoxide (DMSO) to the PH 500 as a buffer layer. The PSC performance was optimized with a 88% improvement over the conventional PSCs (photoactive area: 225 mm2, power conversion efficiency (PCE): 3.2%) by the introduction to the buffer layer of Au NPs and DMSO at 10 wt% and 1.0 wt%, respectively, and with 15 wt% Au NP doping in the photoactive layer. The internal resistance was decreased due to the increased photocurrent caused by the localized surface plasmon resonance (LSPR) effect of the Au NPs in the photoactive layer and by the improvement of carrier mobility induced by the DMSO doping of the buffer layer. As a result, the series resistance (RS) deceased from 42.3 to 19.7 Ω cm2 while the shunt resistance (RSH) increased from 339 to 487 Ω cm2. 相似文献
48.
Materials and Wireless Microfluidic Systems for Electronics Capable of Chemical Dissolution on Demand 下载免费PDF全文
Chi Hwan Lee Jae‐Woong Jeong Yuhao Liu Yihui Zhang Yan Shi Seung‐Kyun Kang Jeonghyun Kim Jae Soon Kim Na Yeon Lee Bong Hoon Kim Kyung‐In Jang Lan Yin Min Ku Kim Anthony Banks Ungyu Paik Yonggang Huang John A. Rogers 《Advanced functional materials》2015,25(9):1338-1343
Electronics that are capable of destroying themselves, on demand and in a harmless way, might provide the ultimate form of data security. This paper presents materials and device architectures for triggered destruction of conventional microelectronic systems by means of microfluidic chemical etching of the constituent materials, including silicon, silicon dioxide, and metals (e.g., aluminum). Demonstrations in an array of home‐built metal‐oxide‐semiconductor field‐effect transistors that exploit ultrathin sheets of monocrystalline silicon and in radio‐frequency identification devices illustrate the utility of the approaches. 相似文献
49.
In Situ X‐Ray Diffraction Studies on Structural Changes of a P2 Layered Material during Electrochemical Desodiation/Sodiation 下载免费PDF全文
Young Hwa Jung Ane S. Christiansen Rune E. Johnsen Poul Norby Do Kyung Kim 《Advanced functional materials》2015,25(21):3227-3237
Sodium layered oxides with mixed transition metals have received significant attention as positive electrode candidates for sodium‐ion batteries because of their high reversible capacity. The phase transformations of layered compounds during electrochemical reactions are a pivotal feature for understanding the relationship between layered structures and electrochemical properties. A combination of in situ diffraction and ex situ X‐ray absorption spectroscopy reveals the phase transition mechanism for the ternary transition metal system (Fe–Mn–Co) with P2 stacking. In situ synchrotron X‐ray diffraction using a capillary‐based microbattery cell shows a structural change from P2 to O2 in P2–Na0.7Fe0.4Mn0.4Co0.2O2 at the voltage plateau above 4.1 V on desodiation. The P2 structure is restored upon subsequent sodiation. The lattice parameter c in the O2 structure decreases significantly, resulting in a volumetric contraction of the lattice toward a fully charged state. Observations on the redox behavior of each transition metal in P2–Na0.7Fe0.4Mn0.4Co0.2O2 using X‐ray absorption spectroscopy indicate that all transition metals are involved in the reduction/oxidation process. 相似文献
50.
Miniaturized Flexible Electronic Systems with Wireless Power and Near‐Field Communication Capabilities 下载免费PDF全文
Jeonghyun Kim Anthony Banks Zhaoqian Xie Seung Yun Heo Philipp Gutruf Jung Woo Lee Sheng Xu Kyung‐In Jang Fei Liu Gregory Brown Junghyun Choi Joo Hyun Kim Xue Feng Yonggang Huang Ungyu Paik John A. Rogers 《Advanced functional materials》2015,25(30):4761-4767
A class of thin, lightweight, flexible, near‐field communication (NFC) devices with ultraminiaturized format is introduced, and systematic investigations of the mechanics, radio frequency characteristics, and materials aspects associated with their optimized construction are presented. These systems allow advantages in mechanical strength, placement versatility, and minimized interfacial stresses compared to other NFC technologies and wearable electronics. Detailed experimental studies and theoretical modeling of the mechanical and electromagnetic properties of these systems establish understanding of the key design considerations. These concepts can apply to many other types of wireless communication systems including biosensors and electronic implants. 相似文献