Relation Between Local Structure, Electric Dipole and Charge Carrier Dynamics in DHICA Melanin, a Model for Biocompatible Semiconductors

2019 ◽  
Author(s):  
Micaela Matta ◽  
Alessandro Pezzella ◽  
Alessandro Troisi
Keyword(s):  
Electronic Structure ◽  
Degrees Of Freedom ◽  
Structural Model ◽  
Computational Study ◽  
Oxidative Polymerization ◽  
Radical Scavenging ◽  
Charge Carriers ◽  
Electronic Charge ◽  
Polymer Semiconductors ◽  
Synthetic Pigments

<div><div><div><p>Eumelanins are a family of natural and synthetic pigments obtained by oxidative polymerization of their natural precursors: 5,6 dihydroxyindole and its 2-carboxy derivative (DHICA). The simultaneous presence of ionic and electronic charge carriers makes these pigments promising materials for applications in bioelectronics. In this computational study we build a structural model of DHICA melanin considering the interplay between its many degrees of freedom, then we examine the electronic structure of representative oligomers. We find that a non-vanishing dipole along the polymer chain sets this system apart from conventional polymer semiconductors, determining its electronic structure, reactivity toward oxidation and localization of the charge carriers. Our work sheds light on previously unnoticed features of DHICA melanin that not only fit well with its radical scavenging and photoprotective properties, but open new perspectives towards understanding and tuning charge transport in this class of materials.<br></p></div></div></div>

Relation Between Local Structure, Electric Dipole and Charge Carrier Dynamics in DHICA Melanin, a Model for Biocompatible Semiconductors

2019 ◽  
Author(s):  
Micaela Matta ◽  
Alessandro Pezzella ◽  
Alessandro Troisi
Keyword(s):  
Electronic Structure ◽  
Degrees Of Freedom ◽  
Structural Model ◽  
Computational Study ◽  
Oxidative Polymerization ◽  
Radical Scavenging ◽  
Charge Carriers ◽  
Electronic Charge ◽  
Polymer Semiconductors ◽  
Synthetic Pigments

<div><div><div><p>Eumelanins are a family of natural and synthetic pigments obtained by oxidative polymerization of their natural precursors: 5,6 dihydroxyindole and its 2-carboxy derivative (DHICA). The simultaneous presence of ionic and electronic charge carriers makes these pigments promising materials for applications in bioelectronics. In this computational study we build a structural model of DHICA melanin considering the interplay between its many degrees of freedom, then we examine the electronic structure of representative oligomers. We find that a non-vanishing dipole along the polymer chain sets this system apart from conventional polymer semiconductors, determining its electronic structure, reactivity toward oxidation and localization of the charge carriers. Our work sheds light on previously unnoticed features of DHICA melanin that not only fit well with its radical scavenging and photoprotective properties, but open new perspectives towards understanding and tuning charge transport in this class of materials.<br></p></div></div></div>

Cobaltites as perspective thermoelectrics

2005 ◽  
Vol 886 ◽  
Author(s):  
Jiri Hejtmánek ◽  
Miroslav Veverka ◽  
Karel Knižek ◽  
Hiroyuki Fujishiro ◽  
Sylvie Hebert ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Phonon Scattering ◽  
Configurational Entropy ◽  
Energy Difference ◽  
Charge Carriers ◽  
Material Research ◽  
Cobalt Ions ◽  
Similar Materials ◽  
Physical Background ◽  
Open Question

AbstractThe recent material research of mixed cobalt oxides is strongly motivated by the potential of some of them to be used as chemically stable high temperature thermoelectric material. This fact together with both the theoretical and experimental ambitions to fulfill the severe criteria needed for efficient thermoelectric conversion intensified both their theoretical and experimental research. Nonetheless, despite the investigations of the prototype materials represented by 3D perovskites Ln1−xAxCoO3 (Ln = La, Y, rare-earth, A = alkaline-earth) and 2D cobaltites of NaxCoO2 type, the concise physical background of their transport and magnetic properties remain still a matter of debate. This is likely due to a fact that cobalt ions can be stabilized either in low-spin state (diamagnetic for “pure” Co3+), with filled t2g levels and empty eg states, or magnetic ones, with filled eg states. As the energy difference between respective states is due to comparable strength of crystal field and Hund's energies rather small, the thermodynamically most stable ground-state, with eventually different character of charge carriers, can be critically influenced by an interplay of additional degrees of freedom - orbital and charge. The challenge for unequivocal theoretical model represents the thermoelectric power of mixed cobaltites where, up to now, somewhat ambiguous models based either on “classical” approach, associated with diffusion of itinerant charge carriers, or more exotic - based on configurational entropy of quasi-itinerant carriers - are often used for similar materials. Simultaneously, the open question remains the assessment of the dominant mechanism of phonon scattering in 2D cobaltites.

Polymorphism and the influence of crystal structure on the luminescence of the opto-electronic material 4,4′-bis(9-carbazolyl)biphenyl

CrystEngComm ◽  
2014 ◽  
Vol 16 (33) ◽  
pp. 7621-7625 ◽  
Author(s):  
Cody J. Gleason ◽  
Jordan M. Cox ◽  
Ian M. Walton ◽  
Jason B. Benedict
Keyword(s):  
Crystal Structure ◽  
Electronic Structure ◽  
Electronic Material ◽  
Single Crystal ◽  
Charge Transport ◽  
Luminescent Properties ◽  
Electronic Structure Calculations ◽  
Electronic Charge ◽  
Single Crystal Structures ◽  
Structure Calculations

Single crystal structures, luminescent properties and electronic structure calculations of three polymorphs of the opto-electronic charge transport material 4,4′-bis(9-carbazolyl)biphenyl.

Effect of Tensile Strain on Performance Parameters of Different Structures of MoS2 Monolayer

2021 ◽  
Author(s):  
Priya kaushal ◽  
Tarun Chaudhary ◽  
Gargi Khanna
Keyword(s):  
Tensile Strain ◽  
Computational Study ◽  
Level Structure ◽  
Charge Carriers ◽  
Performance Parameters ◽  
Mos2 Monolayer ◽  
Higher Temperature ◽  
Silicon Doped ◽  
The Impact ◽  
Biaxial Tensile Strain

Abstract The present work is based on the computational study of MoS2 monolayer and effect of tensile strain on its atomic level structure. The bandgap for MoS2 monolayer, defected MoS2 monolayer and Silicon-doped monolayer are 1.82 eV (direct bandgap), 0.04 (indirect bandgap) and 1.25eV (indirect bandgap), respectively. The impact of tensile strain (0-0.7%) on the bandgap and effective mass of charge carriers of these three MoS2 structure has been investigated. The bandgap decrease of 5.76%, 31.86% and 6.03% has been observed in the three structures for biaxial strain while the impact of uniaxial strain is quite low. The impact of higher temperature on the bandgap under biaxial tensile strain has been also analyzed in this paper. These observations are extremely important for 2D material-based research for electronic applications.

Charge Transport Properties of a Partially Reduced V2O5 Xerogel Intercalated with a Polymer Electrolyte

1995 ◽  
Vol 393 ◽  
Author(s):  
Joyce Albritton Thomas ◽  
Grant M. Kloster ◽  
D. Shriver ◽  
C. R. Kannewurf
Keyword(s):  
Charge Transport ◽  
Transport Properties ◽  
Polymer Electrolyte ◽  
Variable Temperature ◽  
Sol Gel ◽  
Electronic Conductivity ◽  
Charge Carriers ◽  
Electronic Charge ◽  
Ionic Charge ◽  
Intimate Contact

ABSTRACTRecently, there has been considerable interest in advanced materials and processing techniques for practical applications. V2O5 xerogels have generated much attention because they are layered materials that undergo reversible redox intercalation with lithium. The sol-gel process has been used to intercalate V2O5 xerogels with the polymer electrolyte, oxymethylene linked poly(ethylene oxide) - lithium triflate [(a-PEO)n(LiCF3SO3)]. The resulting nanocomposite is a mixed ionic-electronic conductor in which the ionic charge carriers in the polymer electrolyte are in intimate contact with the electronic charge carriers in the V205 xerogel. Variable-temperature electronic conductivity and thermoelectric power measurements have been performed to examine the charge transport properties.

scholarly journals Conformational behavior and electronic structure of silylketenes studied with quantum chemical calculations and photoelectron spectroscopy

1997 ◽  
Vol 75 (12) ◽  
pp. 1851-1861 ◽  
Author(s):  
Heidi M. Muchall ◽  
Nick H. Werstiuk ◽  
Jiangong Ma ◽  
Thomas T. Tidwell ◽  
Kuangsen Sung
Keyword(s):  
Electronic Structure ◽  
Quantum Chemical Calculations ◽  
Photoelectron Spectroscopy ◽  
Quantum Chemical ◽  
Computational Study ◽  
Photoelectron Spectra ◽  
Conformational Behavior ◽  
Torsional Angle ◽  
Orbital Interaction ◽  
Orbital Energies

The He(I) photoelectron spectra of silylketenes (Me3Si)2C=C=O (1), Me5Si2CH=C=O (2), Me2Si(CH=C=O)2 (3), MeSi(CH=C=O)3 (4), (SiMe2CH=C=O)2 (5), and (CH2SiMe2CH=C=O)2 (6) have been recorded and their structures and orbital energies have been calculated by ab initio methods. Orbital energies for disilanes 2 and 5 are strongly dependent on a Si-Si-C-C torsional angle due to σ–π orbital interaction. Comparisons between experimental and simulated spectra show that 2 and 5 prefer conformations in which the Si—Si bond and ketene group(s) are approximately orthogonal (113° and 111°, respectively). Silylalkenes Me5Si2CH=CH2 (7) and (SiMe2CH=CH2)2 (8), which have been included in the computational study, show the same behavior as their corresponding silylketenes. Silylbis- and trisketenes 3–6 do not exhibit π–π interaction of any significance. For Si—Si containing compounds, the best agreement between experimental and computed data was obtained when Becke3LYP/6-31G*//HF/3-21G* was employed. Keywords: conformational behavior, electronic structure, photoelectron spectroscopy, quantum chemical calculations, silylketenes.

A Weighted Rearranged Spectral Equation Method for Structural Model Updating

1995 ◽  
Author(s):  
José Roberto F. Arruda ◽  
Carlson Antonio M. Verçosa
Keyword(s):  
Degrees Of Freedom ◽  
Structural Model ◽  
Model Updating ◽  
Structural Connectivity ◽  
Computational Cost ◽  
Force Balance ◽  
Dynamic Force ◽  
Stiffness Coefficients ◽  
Spring System ◽  
Spectral Equation

Abstract A new structural model updating method based on the dynamic force balance is presented. The method consists of rearranging the spectral equation so that measured modes and natural frequencies can be used to compute directly updated stiffness coefficients. The proposed method preserves both the structural connectivity and reciprocity, which translate into sparsity and symmetry of the stiffness matrix, respectively. Large changes in small-valued stiffness coefficients are avoided using parameter weighting in the rearranged spectral equation solution. It is shown that the proposed method produces results which are similar to the results obtained using Alvar Kabe’s method, with the advantages of simpler formulation and smaller computational cost. A simple example of an 8 degrees-of-freedom mass-spring system, originally used by Kabe to present his method, is used here to evaluate the proposed method.

Electronic Functions in Liquid-Crystalline Nanostructures with High Polarization

MRS Advances ◽  
2019 ◽  
Vol 4 (31-32) ◽  
pp. 1733-1740
Author(s):  
Masahiro Funahashi
Keyword(s):  
Liquid Crystalline ◽  
Carrier Transport ◽  
Ferroelectric Phase ◽  
Photovoltaic Effect ◽  
Charge Carriers ◽  
Side Chain ◽  
Electronic Charge ◽  
Internal Electric Field ◽  
Alkyl Side Chain ◽  
Perylene Bisimide

AbstractMultifunctionality was created by coupling an electronic charge carrier transport with ionic conductivity or ferroelectricity in polarized liquid crystal phases. Liquid-crystalline perylene bisimide derivatives bearing cyclotetrasiloxane rings and triethylene oxide chains formed nanosegregated columnar structures which could conduct ions as well as electrons. The spin-coated thin films could be insolubilized by the exposure on acid vapors and display electrochromism. Phenylterthiophene derivatives bearing a chiral alkyl side chain exhibited a ferroelectric phase, in which a photovoltaic effect was caused by the interaction between photogenerated charge carriers with the internal electric field formed by the spontaneous polarization of the ferroelectric phase.

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