scholarly journals Gated Graphene Electrical Transport Characterization

10.14311/1644 ◽  
2012 ◽  
Vol 52 (5) ◽  
Author(s):  
Josef Náhlík ◽  
Michal Janoušek ◽  
Zbyněk Šobáň
Keyword(s):  
Gate Voltage ◽  
Electrical Transport ◽  
Carrier Mobility ◽  
Room Temperature ◽  
Transparent Material ◽  
Carbon Structure ◽  
Physical Behavior ◽  
Sweep Direction ◽  
New Material ◽  
Higher Carrier Mobility

Graphene is a very interesting new material, and promises attractive applications in future nanodevices. It is a 2D carbon structure with very interesting physical behavior. Graphene is an almost transparent material that has higher carrier mobility than any other material at room temperature. Graphene can therefore be used in applications such as ultrahigh-speed transistors and transparent electrodes. In this paper, we present our preliminary experiments on the transport behavior of graphene at room temperature. We measured the resistivity of Hall-bar samples depending on gate voltage (backgated graphene). Hysteresis between the forward and backward sweep direction was observed.

scholarly journals Structure and Doping Optimization of IDT-Based Copolymers for Thermoelectrics

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1463
Author(s):  
Tongchao Liu ◽  
Dexun Xie ◽  
Jinjia Xu ◽  
Chengjun Pan
Keyword(s):  
Organic Semiconductors ◽  
Carrier Mobility ◽  
Carrier Transport ◽  
Room Temperature ◽  
Charge Carrier Transport ◽  
Structure Property ◽  
Polymer Backbone ◽  
Donor Acceptor ◽  
Higher Carrier Mobility ◽  
The Relationship

π-conjugated backbones play a fundamental role in determining the thermoelectric (TE) properties of organic semiconductors. Understanding the relationship between the structure–property–function can help us screen valuable materials. In this study, we designed and synthesized a series of conjugated copolymers (P1, P2, and P3) based on an indacenodithiophene (IDT) building block. A copolymer (P3) with an alternating donor–acceptor (D-A) structure exhibits a narrower band gap and higher carrier mobility, which may be due to the D-A structure that helps reduce the charge carrier transport obstacles. In the end, its power factor reaches 4.91 μW m−1 K−2 at room temperature after doping, which is superior to those of non-D-A IDT-based copolymers (P1 and P2). These results indicate that moderate adjustment of the polymer backbone is an effective way to improve the TE properties of copolymers.

scholarly journals Demonstration of valley anisotropy utilized to enhance the thermoelectric power factor

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Airan Li ◽  
Chaoliang Hu ◽  
Bin He ◽  
Mengyu Yao ◽  
Chenguang Fu ◽  
...  
Keyword(s):  
Thermoelectric Power ◽  
Power Factor ◽  
Carrier Mobility ◽  
Room Temperature ◽  
Lattice Thermal Conductivity ◽  
Thermoelectric Performance ◽  
First Principles Calculations ◽  
Thermoelectric Power Factor ◽  
Higher Carrier Mobility ◽  
P Type

AbstractValley anisotropy is a favorable electronic structure feature that could be utilized for good thermoelectric performance. Here, taking advantage of the single anisotropic Fermi pocket in p-type Mg3Sb2, a feasible strategy utilizing the valley anisotropy to enhance the thermoelectric power factor is demonstrated by synergistic studies on both single crystals and textured polycrystalline samples. Compared to the heavy-band direction, a higher carrier mobility by a factor of 3 is observed along the light-band direction, while the Seebeck coefficient remains similar. Together with lower lattice thermal conductivity, an increased room-temperature zT by a factor of 3.6 is found. Moreover, the first-principles calculations of 66 isostructural Zintl phase compounds are conducted and 9 of them are screened out displaying a pz-orbital-dominated valence band, similar to Mg3Sb2. In this work, we experimentally demonstrate that valley anisotropy is an effective strategy for the enhancement of thermoelectric performance in materials with anisotropic Fermi pockets.

scholarly journals Backbone Effects on the Thermoelectric Properties of Ultra-Small Bandgap Conjugated Polymers

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2486
Author(s):  
Dexun Xie ◽  
Jing Xiao ◽  
Quanwei Li ◽  
Tongchao Liu ◽  
Jinjia Xu ◽  
...  
Keyword(s):  
Conjugated Polymers ◽  
Power Factor ◽  
Carrier Mobility ◽  
Polymeric Materials ◽  
Thermoelectric Performance ◽  
Organic Thermoelectric Materials ◽  
Higher Power ◽  
Donor Acceptor ◽  
Maximum Power Factor ◽  
Higher Carrier Mobility

Conjugated polymers with narrower bandgaps usually induce higher carrier mobility, which is vital for the improved thermoelectric performance of polymeric materials. Herein, two indacenodithiophene (IDT) based donor–acceptor (D-A) conjugated polymers (PIDT-BBT and PIDTT-BBT) were designed and synthesized, both of which exhibited low-bandgaps. PIDTT-BBT showed a more planar backbone and carrier mobility that was two orders of magnitude higher (2.74 × 10−2 cm2V−1s−1) than that of PIDT-BBT (4.52 × 10−4 cm2V−1s−1). Both exhibited excellent thermoelectric performance after doping with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, where PIDTT-BBT exhibited a larger conductivity (0.181 S cm−1) and a higher power factor (1.861 μW m−1 K−2) due to its higher carrier mobility. The maximum power factor of PIDTT-BBT reached 4.04 μW m−1 K−2 at 382 K. It is believed that conjugated polymers with a low bandgap are promising in the field of organic thermoelectric materials.

scholarly journals Cat-CrNP as new material with catalytic properties for 2-chloro-2-propen-1-ol and ethylene oligomerizations

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jacek Malinowski ◽  
Dagmara Jacewicz ◽  
Artur Sikorski ◽  
Mariusz Urbaniak ◽  
Przemysław Rybiński ◽  
...  
Keyword(s):  
Complex Compound ◽  
Atmospheric Pressure ◽  
Room Temperature ◽  
Organometallic Compounds ◽  
Ethylene Oligomerization ◽  
High Catalytic Activity ◽  
New Material ◽  
Activity Requirement ◽  
Olefin Oligomerization ◽  
Xrd Method

AbstractThe contemporary search for new catalysts for olefin oligomerization and polymerization is based on the study of coordinating compounds and/or organometallic compounds as post-metallocene catalysts. However known catalysts are suffered by many flaws, among others unsatisfactory activity, requirement of high pressure or instability at high temperatures. In this paper, we present a new catalyst i.e. the crystalline complex compound possesing high catalytic activity in the oligomerization of olefins, such as 2-chloro-2-propen-1-ol and ethylene under very mild conditions (room temperature, 0.12 bar for ethylene oligomerization, atmospheric pressure for 2-chloro-2-propen-1-ol oligomerization). New material—Cat-CrNP ([nitrilotriacetato-1,10-phenanthroline]chromium(III) tetrahydrate) has been obtained as crystalline form of the nitrilotriacetate complex compound of chromium(III) with 1,10-phenanthroline and characterized in terms of its crystal structure by the XRD method and by multi-analytical investigations towards its physicochemical propeties The yield of catalytic oligomerization over Cat-CrNP reached to 213.92 g · mmol−1 · h−1· bar−1 and 3232 g · mmol−1 · h−1 · bar−1 for the 2-chloro-2-propen-1-ol and ethylene, respectively. Furthemore, the synthesis of Cat-CrNP is cheap, easy to perform and solvents used during preparation are environmentally friendly.

Room-temperature discotic liquid-crystalline coronene diimides exhibiting high charge-carrier mobility in air

2009 ◽  
Vol 19 (37) ◽  
pp. 6688 ◽  
Author(s):  
Zesheng An ◽  
Junsheng Yu ◽  
Benoit Domercq ◽  
Simon C. Jones ◽  
Stephen Barlow ◽  
...  
Keyword(s):  
Charge Carrier ◽  
Carrier Mobility ◽  
Liquid Crystalline ◽  
Room Temperature ◽  
Charge Carrier Mobility ◽  
High Charge ◽  
High Charge Carrier Mobility

Structural and electrical properties of KCa2Nb5O15 ceramics

Open Physics ◽  
2008 ◽  
Vol 6 (2) ◽  
Author(s):  
Banarji Behera ◽  
Pratibindhya Nayak ◽  
Ram Choudhary
Keyword(s):  
Electrical Properties ◽  
Temperature Variation ◽  
Electrical Transport ◽  
Room Temperature ◽  
Complex Impedance ◽  
Tungsten Bronze ◽  
Transport Processes ◽  
Relaxation Processes ◽  
Orthorhombic Crystal Structure ◽  
Grain Distribution

AbstractA polycrystalline sample of KCa2Nb5O15 with tungsten bronze structure was prepared by a mixed oxide method at high temperature. A preliminary structural analysis of the compound showed an orthorhombic crystal structure at room temperature. Surface morphology of the compound shows a uniform grain distribution throughout the surface of the sample. Studies of temperature variation on dielectric response at various frequencies show that the compound has a transition temperature well above the room temperature (i.e., 105°C), which was confirmed by the polarization measurement. Electrical properties of the material have been studied using a complex impedance spectroscopy (CIS) technique in a wide temperature (31–500°C) and frequency (102–106 Hz) range that showed only bulk contribution and non-Debye type relaxation processes in the material. The activation energy of the compound (calculated from both the loss and modulus spectrum) is same, and hence the relaxation process may be attributed to the same type of charge carriers. A possible ‘hopping’ mechanism for electrical transport processes in the system is evident from the modulus analysis. A plot of dc conductivity (bulk) with temperature variation demonstrates that the compound exhibits Arrhenius type of electrical conductivity.

Electric and thermoelectric properties of CdTe/PbTe epitaxial nanocomposite

2014 ◽  
Vol 07 (06) ◽  
pp. 1440007
Author(s):  
Michal Szot ◽  
Krzysztof Dybko ◽  
Piotr Dziawa ◽  
Leszek Kowalczyk ◽  
Viktor Domukhovski ◽  
...  
Keyword(s):  
Thermoelectric Properties ◽  
Carrier Mobility ◽  
Room Temperature ◽  
Molecular Beam ◽  
High Quality ◽  
Polycrystalline Solid ◽  
Hall Effect Measurements ◽  
Shubnikov De Haas Oscillations

The electric and thermoelectric properties of novel, CdTe / PbTe layered nanocomposite material are investigated. The molecular beam epitaxy (MBE) method was used for preparation of samples with well controlled distances (from 20 to 70 nm) between the layers of CdTe nanograins embedded in PbTe thermoelectric matrix as well as with number of these layers from 2 to 10. The Hall effect measurements performed in temperature range from 4–300 K revealed that carrier mobility is strongly affected by scattering on CdTe grain boundaries. The observation of Shubnikov-de Haas oscillations confirms high quality of the samples and allows determination of effective mass of conducting electrons m* = 0.04m0. The measurements of the room temperature Seebeck coefficient together with electrical conductivity lead to the power factors which are comparable to those reported in PbTe / CdTe polycrystalline solid solutions.

scholarly journals Подвижность ионных носителей заряда в пьезоэлектрических кристаллах Li-=SUB=-2-=/SUB=-B-=SUB=-4-=/SUB=-O-=SUB=-7-=/SUB=-

2020 ◽  
Vol 62 (3) ◽  
pp. 386
Author(s):  
Н.И. Сорокин ◽  
Ю.В. Писаревский ◽  
В.В. Гребенев ◽  
В.А. Ломонов
Keyword(s):  
Crystal Lattice ◽  
Carrier Mobility ◽  
Room Temperature ◽  
Lithium Ion ◽  
Structural Data ◽  
Crystallographic Axis ◽  
Frequency Range ◽  
Impedance Measurements ◽  
Structural Mechanism ◽  
Ag Electrodes

The impedance measurements of Li2B4O7 single crystal with Ag electrodes in the frequency range 1-3*107 Hz at room temperature have been made. The Li2B4O7 crystal (sp. gr. I41cd, Z = 8) was oriented along crystallographic axis c. Contributions from the bulk crystal and crystal / electrode boundaries in the impedance hodograph of the Ag | Li2B4O7 | Ag system were selected. The structural mechanism of lithium-ion transport in Li2B4O7 has been discussed. Based on electrophysical and structural data, the conductivity σdc = 2.3 × 10–9 S / cm, carrier mobility (vacancies VLi) μmob = 6 × 10−10 cm2 / sV and their concentration nmob = 2.4 × 1019 cm – 3 (0.14% of the amount of lithium in the crystal lattice) have been determined.

The Potential of Graphene in Electronic Applications

2020 ◽  
Vol 976 ◽  
pp. 121-130 ◽  
Author(s):  
Ze Kai Sun
Keyword(s):  
Charge Carrier ◽  
Carrier Mobility ◽  
Hexagonal Boron Nitride ◽  
Chemical Vapour ◽  
Charge Carrier Mobility ◽  
Electrical Performance ◽  
High Charge ◽  
Exfoliated Graphene ◽  
New Material ◽  
High Charge Carrier Mobility

2D materials have emerged as new material used in electronic devices. Graphene has attract great attention due to its high charge carrier mobility and thin thickness. Different production methods have been used to produce graphene used in different electronic applications. This work highlights the validity of graphene electronic applications and drawbacks that needed to be overcome in the future. Chemical vapour deposition (CVD) grew graphene show great potential in replacing ITO in touch screen with low sheet resistance, flexibility and high transparency. Screen printed touchpad flexible keyboard can be fabricated directly from graphene inks. Graphene based touch-pad show a good conductive and flexibility while providing stable electrical performance under bending and change of humidity. Mechanical exfoliated graphene exhibits high charge carrier mobility by encapsulated with hexagonal boron nitride (h-BN).

2D planar penta-MN2 (M = Pd, Pt) sheets identified through structure search

2019 ◽  
Vol 21 (1) ◽  
pp. 246-251 ◽  
Author(s):  
Kexian Zhao ◽  
Xiaoyin Li ◽  
Shuo Wang ◽  
Qian Wang
Keyword(s):  
Carrier Mobility ◽  
Structure Search ◽  
Higher Carrier Mobility

Planar penta-MN2 sheets are energetically more stable than pyrite MN2, and penta-PtN2 has higher carrier mobility than phosphorene.

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