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271.
Zinc chalcogenide which includes zinc selenide,zinc sulphide,zinc telluride and mixed crystals of these shows a great potential as an optoelectronic device material. Zinc selenotelluride is a suitable material for visible light emitting devices which are expected to cover the spectral range from yellow to blue. In our present study the composition controlled ZnSe1-xTex films with different Te content x = 0,0.2,0.4,0.6,0.8 and 1.0 were deposited by electron beam (EB) evaporation technique. GaAs films were de... 相似文献
272.
273.
《国际聚合物材料杂志》2012,61(11):825-836
Poly(9-dodecylcarbazole) (PDDC) and poly[(9-dodecylcarbazole)-co-thiophene] (PDDCT) were synthesized via oxidative coupling method using FeCl3 and the polymers exhibited good solubility in polar aprotic solvents. The synthesized polymers were characterized using UV-visible, FTIR, 1H-NMR spectroscopic techniques. The polymers exhibited thermal stability up to 300°C. The absorption spectra showed the maximum absorption peak at 414 and 443 nm (λmax), respectively, for PDDC and PDDCT. The electrochemical analysis revealed that the band gaps calculated for PDDC and PDDCT are 2.21 eV and 1.91 eV, respectively. The study of anodic peak current against scan rate showed that the electrochemical process is diffusion-limited. 相似文献
274.
Ajay Virkar Stefan Mannsfeld Joon Hak Oh Michael F. Toney Yih Horng Tan Gang‐yu Liu J. Campbell Scott Robert Miller Zhenan Bao 《Advanced functional materials》2009,19(12):1962-1970
In organic thin film transistors (OTFTs), charge transport occurs in the first few monolayers of the semiconductor near the semiconductor/dielectric interface. Previous work has investigated the roles of dielectric surface energy, roughness, and chemical functionality on performance. However, large discrepancies in performance, even with apparently identical surface treatments, indicate that additional surface parameters must be identified and controlled in order to optimize OTFTs. Here, a crystalline, dense octadecylsilane (OTS) surface modification layer is found that promotes two‐dimensional semiconductor growth. Higher mobility is consistently achieved for films deposited on crystalline OTS compared to on disordered OTS, with mobilities as high as 5.3 and 2.3 cm2 V?1 s?1 for C60 and pentacene, respectively. This is a significant step toward morphological control of organic semiconductors which is directly linked to their thin film charge carrier transport. 相似文献
275.
S. Xiao M. Nguyen X. Gong Y. Cao H. Wu D. Moses A.J. Heeger 《Advanced functional materials》2003,13(1):25-29
Polyhedral oligomeric silsesquioxanes (POSS) anchored to poly(2‐methoxy‐5‐(2‐ethylhexyloxy)‐1.4‐phenylenevinylene) (MEH‐PPV) (MEH‐PPV–POSS), and to poly(9,9‐dihexylfluorenyl‐2,7‐diyl) (PFO) (PFO–POSS) were synthesized. Compared with the corresponding parent polymers, MEH‐PPV and PFO, MEH‐PPV–POSS and PFO–POSS have better thermal stability. MEH‐PPV–POSS and MEH‐PPV have identical absorption and photoluminescent (PL) spectra, both in solution and as thin films. They also have identical electroluminescent (EL) spectra. Devices made from MEH‐PPV–POSS exhibit higher brightness (1320 cd m–2 at 3.5 V) and higher external quantum efficiency (ηext = 2.2 % photons per electron) compared to MEH‐PPV (230 cd m–2 at 3.5 V and ηext = 1.5 % ph el–1). Compared with PFO in the same device configuration, PFO–POSS has improved blue EL emission and higher ηext. 相似文献
276.
The effects of chloride ion on the electrochemical behavior and the semiconducting properties of the passive film on supermartensitic stainless steel in 0. 5 mol/L NaHCO3 solution were investigated using potentiodynamic polarization, the potentiostatic current transients and Mott-Schottky analysis. The results indicated that chloride ion narrowed passivation region and improved pitting susceptibility. The steady state current densities were independent of film-formed potentials, which was in good agreement with the assumption of the point defect model (PDM). The capacitance results showed the fact that the passive films had a multilayer character. The defect density decreased with increasing passive film formation potential. The chloride ion induced changes of the acceptor densities and donor densities of the passive films. 相似文献
277.
High Current Injection into Dynamic p–n Homojunction in Polymer Light‐Emitting Electrochemical Cells 下载免费PDF全文
Tomo Sakanoue Jinpeng Li Hisaaki Tanaka Ryota Ito Shimpei Ono Shin‐ichi Kuroda Taishi Takenobu 《Advanced materials (Deerfield Beach, Fla.)》2017,29(18)
Ions and electrons in blends of polymer–electrolyte can work in ensemble to operate light‐emitting electrochemical cells (LECs), in which the unique features of in situ formed p–n homojunctions offer efficient charge injection and transport. However, electrochemical features give rise to significant stability and speed issues due to limited electrochemical stability and low ion mobility, resulting in low brightness and a slow response of LECs. Here, these issues are overcome by the separate control of ionic and electronic charges, using a simple driving pulse superimposed on a small base voltage; ions with slow response are rearranged by a constant base voltage, while a high‐voltage pulse, superimposed upon the base, injects electrons/holes which have fast response, with minimal effect on the ions. This scheme successfully injects an extremely high current density of > 2 kA cm?2 with a balanced electron/hole ratio, at a high‐speed response time of ≈ 50 ns; both properties demonstrate advantages of LECs in making polymers brighter. An in situ electron spin resonance measurement on the LECs further revealed that this impressive performance is due to the highly doped polymers, whose spin density reached 7 × 1019 spins cm?3, and an ordered polymer structure in the active layer blend. 相似文献
278.
Functional Single‐Walled Carbon Nanotubes and Nanoengineered Networks for Organic‐ and Perovskite‐Solar‐Cell Applications 下载免费PDF全文
David R. Barbero Samuel D. Stranks 《Advanced materials (Deerfield Beach, Fla.)》2016,28(44):9668-9685
Carbon nanotubes have a variety of remarkable electronic and mechanical properties that, in principle, lend them to promising optoelectronic applications. However, the field has been plagued by heterogeneity in the distributions of synthesized tubes and uncontrolled bundling, both of which have prevented nanotubes from reaching their full potential. Here, a variety of recently demonstrated solution‐processing avenues is presented, which may combat these challenges through manipulation of nanoscale structures. Recent advances in polymer‐wrapping of single‐walled carbon nanotubes (SWNTs) are shown, along with how the resulting nanostructures can selectively disperse tubes while also exploiting the favorable properties of the polymer, such as light‐harvesting ability. New methods to controllably form nanoengineered SWNT networks with controlled nanotube placement are discussed. These nanoengineered networks decrease bundling, lower the percolation threshold, and enable a strong enhancement in charge conductivity compared to random networks, making them potentially attractive for optoelectronic applications. Finally, SWNT applications, to date, in organic and perovskite photovoltaics are reviewed, and insights as to how the aforementioned recent advancements can lead to improved device performance provided. 相似文献
279.
Organic Semiconducting Macromolecular Dyes for NIR-II Photoacoustic Imaging and Photothermal Therapy
Chao Yin Xiaozhen Li Yi Wang Yuying Liang Shan Zhou Pengchao Zhao Chun-Sing Lee Quli Fan Wei Huang 《Advanced functional materials》2021,31(37):2104650
Owing to the unique advantages of photoacoustic imaging (PAI) and photothermal therapy (PTT) conducted over the near-infrared-II (NIR-II) window, the development of high-efficiency optical agents with NIR-II light responsiveness is of great significance. Despite the diversity of optical agents developed for NIR-II PAI and PTT, most of them are based on inorganic nanomaterials and small molecular dyes, whose biosafety and photostability need to be further assessed, respectively. Organic semiconducting macromolecular dyes (OSMDs) featuring a large semiconducting backbone are becoming alternative candidates for NIR-II PAI and PTT owing to their reliable biocompatibility, durable photostability, and ideal photothermal conversion capability. This paper reviews the current progress of OSMD-based PAI and PTT in the NIR-II optical window. The three main types of OSMDs with different skeleton architectures are introduced, and their applications for NIR-II PAI (tumor imaging, stem cell tracking, and vasculature imaging) and PTT (tumor ablation) are described. Viable strategies for further improving the NIR-II PAI performance of OSMDs are discussed. Finally, some major issues faced by OSMDs in NIR-II PAI and PTT are raised, and the future development directions of OSMDs are analyzed. 相似文献
280.
Min Jin Kang Minyeong Kim Eui Sun Hwang Jiwhan Noh Sung Tae Shin Byoung‐Ho Cheong 《Journal of the Society for Information Display》2019,27(1):34-40
Laser crystallization of a 50‐nm thick amorphous‐Si (a‐Si) thin film on glass substrate was examined by a Nd:YAG (λ = 1064 nm) nanosecond laser and a two‐beam laser interference method. In spite of the low absorption rate of the laser wavelength in the a‐Si, crystallized Si ripple patterns were observed following a single laser pulse irradiation. The atomic force microscope (AFM) measurement revealed that surface ripple arrays are protruded as high as 120 nm at the positions corresponding to the maximum laser intensity and the ripples are composed of narrow double peaks with a separation of 1 μm. Raman image mapping was used to plot the spatial distribution of the crystallized Si phase. It was found that a 1064‐nm‐wavelength nanosecond laser could crystallize an a‐Si thin film into polycrystalline‐Si (poly‐Si) by nonlinear absorption under high laser energy irradiation. 相似文献