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Hugosson, Håkan W.
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Elgammal, K., Hugosson, H. W., Smith, A. D., Råsander, M., Bergqvist, L. & Delin, A. (2017). Density functional calculations of graphene-based humidity and carbon dioxide sensors: effect of silica and sapphire substrates. Surface Science, 663, 23-30
Öppna denna publikation i ny flik eller fönster >>Density functional calculations of graphene-based humidity and carbon dioxide sensors: effect of silica and sapphire substrates
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2017 (Engelska)Ingår i: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 663, s. 23-30Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

We present dispersion-corrected density functional calculations of water and carbon dioxide molecules adsorption on graphene residing on silica and sapphire substrates. The equilibrium positions and bonding distances for the molecules are determined. Water is found to prefer the hollow site in the center of the graphene hexagon, whereas carbon dioxide prefers sites bridging carbon-carbon bonds as well as sites directly on top of carbon atoms. The energy differences between different sites are however minute – typically just a few tenths of a millielectronvolt. Overall, the molecule-graphene bonding distances are found to be in the range 3.1–3.3 Å. The carbon dioxide binding energy to graphene is found to be almost twice that of the water binding energy (around 0.17 eV compared to around 0.09 eV). The present results compare well with previous calculations, where available. Using charge density differences, we also qualitatively illustrate the effect of the different substrates and molecules on the electronic structure of the graphene sheet.

Nyckelord
Graphene; DFT; Sensor; Humidity; Carbon dioxide
Nationell ämneskategori
Materialteknik
Identifikatorer
urn:nbn:se:hig:diva-24190 (URN)10.1016/j.susc.2017.04.009 (DOI)000405043300004 ()2-s2.0-85018431677 (Scopus ID)
Tillgänglig från: 2017-06-13 Skapad: 2017-06-13 Senast uppdaterad: 2018-03-13Bibliografiskt granskad
Mirsakiyeva, A., Hugosson, H. W., Crispin, X. & Delin, A. (2017). Quantum Molecular Dynamical Calculations of PEDOT 12-Oligomer and its Selenium and Tellurium Derivatives. Paper presented at 35th International Conference on Thermoelectrics (ICT), Wuhan, China, 2016. Journal of Electronic Materials, 46(5), 3071-3075
Öppna denna publikation i ny flik eller fönster >>Quantum Molecular Dynamical Calculations of PEDOT 12-Oligomer and its Selenium and Tellurium Derivatives
2017 (Engelska)Ingår i: Journal of Electronic Materials, ISSN 0361-5235, E-ISSN 1543-186X, Vol. 46, nr 5, s. 3071-3075Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

We present simulation results, computed with the Car–Parrinello molecular dynamics method, at zero and ambient temperature (300 K) for poly(3,4-ethylenedioxythiophene) [PEDOT] and its selenium and tellurium derivatives PEDOS and PEDOTe, represented as 12-oligomer chains. In particular, we focus on structural parameters such as the dihedral rotation angle distribution, as well as how the charge distribution is affected by temperature. We find that for PEDOT, the dihedral angle distribution shows two distinct local maxima whereas for PEDOS and PEDOTe, the distributions only have one clear maximum. The twisting stiffness at ambient temperature appears to be larger the lighter the heteroatom (S, Se, Te) is, in contrast to the case at 0 K. As regards point charge distributions, they suggest that aromaticity increases with temperature, and also that aromaticity becomes more pronounced the lighter the heteroatom is, both at 0 K and ambient temperature. Our results agree well with previous results, where available. The bond lengths are consistent with substantial aromatic character both at 0 K and at ambient temperature. Our calculations also reproduce the expected trend of diminishing gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital with increasing atomic number of the heteroatom.

Nyckelord
Aromatization; Atoms; Charge distribution; Density functional theory; Molecular dynamics; Molecular orbitals; Selenium; Tellurium; Tellurium compounds; Temperature, Dynamical calculations; Highest occupied molecular orbital; Lowest unoccupied molecular orbital; Molecular dynamics methods; PEDOS; PEDOT; PEDOTe; Poly-3, 4-ethylenedioxythiophene, Dihedral angle
Nationell ämneskategori
Elektroteknik och elektronik
Identifikatorer
urn:nbn:se:hig:diva-23282 (URN)10.1007/s11664-016-5161-6 (DOI)000398937900075 ()2-s2.0-85001037983 (Scopus ID)
Konferens
35th International Conference on Thermoelectrics (ICT), Wuhan, China, 2016
Forskningsfinansiär
VetenskapsrådetKungliga VetenskapsakademienKnut och Alice Wallenbergs StiftelseCarl Tryggers stiftelse för vetenskaplig forskning Energimyndigheten
Anmärkning

Funders: Vetenskapsradet (VR), The Royal Swedish Academy of Sciences (KVA), the Knut and Alice Wallenberg Foundation (KAW), Carl Tryggers Stiftelse (CTS), Swedish Energy Agency (STEM), Swedish Foundation for Strategic Research (SSF), and Erasmus Mundus Action 2 TARGET II consortium

Tillgänglig från: 2017-01-12 Skapad: 2017-01-11 Senast uppdaterad: 2018-03-13Bibliografiskt granskad
Mirsakiyeva, A., Hugosson, H. W., Linares, M. & Delin, A. (2017). Temperature dependence of band gaps and conformational disorder in PEDOT and its selenium and tellurium derivatives: Density functional calculations. Journal of Chemical Physics, 147(13), Article ID 134906.
Öppna denna publikation i ny flik eller fönster >>Temperature dependence of band gaps and conformational disorder in PEDOT and its selenium and tellurium derivatives: Density functional calculations
2017 (Engelska)Ingår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 147, nr 13, artikel-id 134906Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

The conducting polymer poly(3,4-ethylenedioxythiophene), or PEDOT, is an attractive material for flexible electronics. We present combined molecular dynamics and quantum chemical calculations, based on density functional theory, of EDOT oligomers and isoelectronic selenium and tellurium derivatives (EDOS and EDOTe) to address the effect of temperature on the geometrical and electronic properties of these systems. With finite size scaling, we also extrapolate our results to the infinite polymers, i.e., PEDOT, PEDOS, and PEDOTe. Our computations indicate that the most favourable oligomer conformations at finite temperature are conformations around the flat trans-conformation and a non-flat conformation around 45° from the cis-conformation. Also, the dihedral stiffness increases with the atomic number of the heteroatom. We find excellent agreement with experimentally measured gaps for PEDOT and PEDOS. For PEDOT, the gap does not increase with temperature, whereas this is the case for its derivatives. The conformational disorder and the choice of the basis set both significantly affect the calculated gaps.

Nationell ämneskategori
Fysik
Identifikatorer
urn:nbn:se:hig:diva-25412 (URN)10.1063/1.4998509 (DOI)000412321600030 ()28987116 (PubMedID)2-s2.0-85031789300 (Scopus ID)
Forskningsfinansiär
VetenskapsrådetKungliga VetenskapsakademienKnut och Alice Wallenbergs StiftelseCarl Tryggers stiftelse för vetenskaplig forskning Energimyndigheten
Anmärkning

Ytterligare finansiär:

Swedish Foundation for Strategic Research (SSF) 

Tillgänglig från: 2017-10-16 Skapad: 2017-10-16 Senast uppdaterad: 2018-03-13Bibliografiskt granskad
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