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Stretchable Conjugated Polymers: A Case Study in Topic Selection for New Research Groups
摘要： The field of π-conjugated (semiconducting) polymers has been underwritten largely because of the promise of flexible (and increasingly, stretchable) devices for energy and health care. Our research group has spent much of the past six years studying the mechanical properties of conjugated polymers. Mechanically robust materials can extend the life spans of devices such as solar cells and organic light-emitting diode (OLED) panels and enable high throughput processing techniques such as roll-to-roll printing. Additionally, wearable and implantable devices, including electronic skin, implantable pressure sensors, and haptic actuators, benefit by having moduli and extensibilities close to those of biological tissue. At the time of our laboratory’s inception, however, the optoelectronic properties of conjugated polymers were understood in much greater depth than their mechanical properties. We therefore set out, as our laboratory’s first research topic, to understand the molecular and microstructural determinants of the mechanical properties of conjugated polymers. This is an Account not only of our scientific findings but also of the pragmatic aspects, including personnel, funding, and time constraints, behind our studies as a nascent research group. We hope that this Account will provide information to newly independent scientists about the process of starting a new research laboratory.
关键词： π-conjugated polymers,stretchable electronics,organic semiconductors,mechanical properties,wearable devices
更新于2025-09-10 09:29:36
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A simple and robust approach to reducing contact resistance in organic transistors
摘要： Efficient injection of charge carriers from the contacts into the semiconductor layer is crucial for achieving high-performance organic devices. The potential drop necessary to accomplish this process yields a resistance associated with the contacts, namely the contact resistance. A large contact resistance can limit the operation of devices and even lead to inaccuracies in the extraction of the device parameters. Here, we demonstrate a simple and efficient strategy for reducing the contact resistance in organic thin-film transistors by more than an order of magnitude by creating high work function domains at the surface of the injecting electrodes to promote channels of enhanced injection. We find that the method is effective for both organic small molecule and polymer semiconductors, where we achieved a contact resistance as low as 200 Ωcm and device charge carrier mobilities as high as 20 cm2V?1s?1, independent of the applied gate voltage.
关键词： contact resistance,organic transistors,charge injection,high work function domains,organic semiconductors
更新于2025-09-10 09:29:36
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Single Crystal Growth and Characterization of the Chalcopyrite Semiconductor CuInTe2 for Photoelectrochemical Solar Fuel Production
摘要： Transition metal chalcogenides are a promising family of materials for applications as photocathodes in photoelectrochemical (PEC) H2 generation. A long-standing challenge for chalcopyrite semiconductors is characterizing their electronic structure—both experimentally and theoretically—due to their relatively high energy bandgaps and spin orbit coupling (SOC), respectively. In this work, we present single crystals of CuInTe2, whose relatively small optically measured bandgap of 0.9 ± 0.03 eV enables electronic structure characterization by angle-resolved photoelectron spectroscopy (ARPES) in conjunction with first-principle calculations incorporating SOC. ARPES measurements reveal bands that are steeply dispersed in energy with a band velocity of 2.5-5.4 x 105 m/s, almost 50% of the extremely conductive material graphene. Additionally, CuInTe2 single crystals are fabricated into electrodes to experimentally determine the valence band edge energy and confirm the thermodynamic suitability of CuInTe2 for water redox chemistry. The electronic structure characterization and band edge position presented in this work provide kinetic and thermodynamic factors that support CuInTe2 as a strong candidate for water reduction.
关键词： photoelectrochemical H2 generation,electronic structure,spin orbit coupling,chalcopyrite semiconductors,band velocity,valence band edge energy,Transition metal chalcogenides,angle-resolved photoelectron spectroscopy,water redox chemistry,CuInTe2
更新于2025-09-10 09:29:36
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Nonlinear optical susceptibility of atomically thin WX2 crystals
摘要： We have studied tungsten diselenide (WSe2) and tungsten disulfide (WS2) monolayer materials in second harmonic generation spectroscopy and microscopy experiments. Ultra-broadband continuum pulses served as the fundamental beam while its second harmonic spectrum in the visible and ultraviolet (UV) range was detected and analyzed with a better than 0.3 nm spectral resolution (< 2 meV). We provide dispersion data and absolute values for χ(2) for the materials within a photon energy range of 2.3–3.2 eV. Fine spectral features that were detected within the dispersion data for the optical nonlinearities indicate the impact of near bandgap exciton transitions. The fundamental bandgap of 2.35 eV and exciton binding energy of 0.38 eV were determined from the measurements for WS2 monolayers while the corresponding values in WSe2 monolayers were 2.22 eV and 0.71 eV. Ranges for the absolute values of the sheet nonlinearity for WS2 and WSe2 are shown to be 0.58–1.65 × 10?18 m2/V and 0.21–0.92 × 10?18 m2/V, correspondingly.
关键词： Nonlinear spectroscopy and microscopy,Transition metal dichalcogenides,Two-dimensional semiconductors,Second harmonic generation,Optical nonlinearity in semiconductors,Monolayer crystals,Optics at interfaces
更新于2025-09-09 09:28:46
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Reference Module in Materials Science and Materials Engineering || Nano-Structured Diluted Magnetic Semiconductors
摘要： Diluted magnetic semiconductors (DMS) materials have attracted much interest in recent years because of the combination of both semiconducting and magnetic properties within the same material. Among the potential applications that DMS materials can offer is spintronics which exploits both the electron charge associated with the intrinsic spin of the electron. DMS are semiconductors doped with magnetic impurities. Physical properties, like band gap energy or magnetism, are now not only a function of the particle size but also of the doping level. Therefore, ordered arrays of nanometer sized magnetic semiconductors are promising components for new devices in magneto- or spin electronics.
关键词： Diluted magnetic semiconductors,Band gap energy,Spintronics,Nanometer sized magnetic semiconductors,Magnetic impurities
更新于2025-09-09 09:28:46
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[Nanostructure Science and Technology] Nanowire Electronics || Properties Engineering of III–V Nanowires for Electronic Application
摘要： Semiconductors have been the core materials of many technological advances in recent years. Silicon, the most studied and used semiconducting material, has been the center of semiconductor industry for decades because it is available abundantly and easy to dope, and silicon dioxide is a superior dielectric material in microelectronic industry. This material can be used to make computer chips, optoelectronics devices, and solar cell. Silicon reshapes the way we live and is unarguably one of the most important materials in modern society. Through its dominant role in the semiconductor industry for now, the search for alternatives is fueled by the unstoppable demand for high-performance and low-power electronics. Among different kinds of semiconductors, III–V semiconductor holds promising properties for replacing silicon, and in particular, the NW structure of III–V semiconductor has been studied extensively.
关键词： nanowire field-effect transistor,semiconductors,contact engineering,crystal engineering,III–V nanowires,surface modification,electronic application
更新于2025-09-09 09:28:46
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Raman scattering studies on very thin layers of gallium sulfide (GaS) as a function of sample thickness and temperature.
摘要： Gallium sulfide is a semiconducting material with a layered structure and a characteristic low interlayer interaction. Because of weak van der Waals forces, GaS crystals are relatively easy to exfoliate to very thin layers. In this work nanometric-GaS layers were obtained by a micro-mechanical exfoliation process and were transferred to Si/SiO2 substrate. The thickness of these layers was estimated from AFM measurements. Raman spectra were collected for different layer thicknesses ranging from one layer to bulk crystal. An analytical function fitted to experimental data is proposed to determine layer thickness from Raman measurements. For the first time, the Raman position and the FWHM of the main Raman peaks were measured on very thin GaS layers as a function of temperature in the range from 80 to 470 K. The first order temperature coefficients of the A1g Raman peaks were determined. Phonon decay due to anharmonic processes at temperatures above 300 K in layers of thickness below 4 nm was observed. Contribution of optical phonon scattering processes to thermal properties of very thin GaS layers is discussed.
关键词： GaS monolayer,anharmonic decay,metal III chalcogenides,layered 2d semiconductors,phonon lifetime
更新于2025-09-09 09:28:46
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First principle analysis for magnetic properties of noble metal doped rutile TiO2
摘要： From first principle analysis, it is shown that non-magnetic TiO2 can be made magnetic using successive doping of Ag and Au at Ti-site. However, Pt-doped TiO2 remains magnetically inert. Effect of another defect in the form of oxygen vacancy adjacent to doped atom has also been carried out. To quantify effect of doping; magnetic moment, Gibbs free energy and defect formation energy has been calculated for each structure. Further, for both the dopants the spin-spin interaction studies reveal that the ferromagnetic (FM) spin ordered system is more stable than the anti ferromagnetic (AFM) one. These theoretical calculations will be used to choose proper ways of chemical synthesis for Ag and Au doped TiO2.
关键词： Magnetic semiconductors,Density-functional theory,Defects
更新于2025-09-09 09:28:46
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The Study of Features of Formation and Properties of A3B5 Semiconductors Highly Doped with Iron
摘要： Layers of InAs, InSb, and GaSb semiconductors highly doped with iron during their growth by the method of pulsed laser deposition are studied experimentally. The best temperatures for layer formation on GaAs (100) substrates are: 250°C (InSb : Fe), 300°C (InAs : Fe), and 350°C (GaSb : Fe). At high Fe concentration (over 10 at %) the layers display ferromagnetic properties expressed in emergence of a hysteresis curve within the magnetic field dependences of the Hall resistance, negative magnetoresistance, and in some cases, ferromagnetic-type magnetization at measurements at room temperature. The atoms of iron do not change the type of layer conductivity; InAs : Fe and InSb : Fe layers possess n-type conductivity, and GaSb : Fe layers display p-type conductivity due to their intrinsic point defects.
关键词： Hall effect,A3B5 semiconductors,ferromagnetic properties,magnetoresistance,iron doping,pulsed laser deposition
更新于2025-09-09 09:28:46
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Facile Synthesis and Characterization of Crystalline Iron Phthalocyanine
摘要： Iron phthalocyanine (FePc) has been successfully synthesized by a solvothermal method using 1, 8-Diazabicyclo [5.4.0] undec-7-ene as the catalyst. The crystal structure and the morphology of FePc powder were systematically characterized by X-ray diffraction, Fourier transform infrared spectrometer, ultraviolet-visible absorption spectra and field emission scanning electron microscopy with energy-dispersive spectrometer, respectively. The FePc with a pure β phase is observed with a large yield up to 80%. It shows a rod-like shape in the microstructure. The length is in the range of 200–600 μm and the width is of 5-20 μm. The present FePc could have potential applications for micro-electronic devices.
关键词： Semiconductors,Crystal growth,Electronic materials
更新于2025-09-09 09:28:46