Investigations concerning the work function of doped graphite

Kyas, A.; Fleischhauer, J.; Steinmetz, Eberhard; Wilhelmi, Herbert

doi:10.1007/bf01466043

Cited by 9 publications

(8 citation statements)

References 4 publications

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“…It is evident that, as the number of conjugated carbon atoms increases, the electronegativity becomes constant. For graphite, two experimental values (3.93 and 4.8 eV) for the mean electron work function were previously reported. , Two approximations were also employed in order to theoretically deduce the electron work function. In the first, it is equal to the HOMO energy (defined for semiconducting carbon tubes); as the HOMO energy is equal to the ionization energy (within the ionizations theorems of Perdew et al; see ref ), the ionization energy for large systems can be considered to be equivalent to the electron work function.…”

Section: Resultsmentioning

confidence: 99%

“…On the other hand, it was reported previously that many properties pertaining to large polynuclear aromatics must approach those of graphite at its largest size limit. − Among these properties are included the ionization energy and electron affinity, both of which are expected to approach the work function of graphite. However, in the case of linear polyene-conjugated systems, no previous reports exist that are focused on clarifying how various properties observed in graphite differ from those of smaller molecules.…”

Section: Introductionmentioning

confidence: 99%

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Donator−Acceptor Map and Work Function for Linear Polyene-Conjugated Molecules. A Density Functional Approximation Study

Martı́nez

2009

J. Phys. Chem. B

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Carotenoids are one particular type of conjugated chromophores with a great capacity for accepting electrons. The question posed here is how the capacity to accept electrons is related to extension of the conjugation. If there is a connection, any chromophore should represent a good antiradical, a point of interest for those investigating the biological effects of antioxidants. In order to analyze the relationship between the extension of the conjugation and the absorbance and electron-donor properties described in this paper, full geometry optimizations at the BPW91/D5DVZ level of theory are reported for a number of linear conjugated polyene systems. Maximum wavelengths were obtained using the TDDFT methodology. From these results, it is possible to conclude that large conjugated chromophores have a great capacity for accepting electrons but diminished power for donating electrons. Apparently, any chromophore should be a good antiradical, but various mechanisms exist for scavenging free radicals. In the case of linear polyene-conjugated molecules, indigo, blue, and green chromophores represent good antiradicals because they are also good antioxidants (effective electron donors). Yellow and red chromophores represent good antiradicals because they are good antireductants (effective electron acceptors). In the case of the molecules reported in this paper, the ionization energy and the electron affinity come close to the work function of graphite. This may be important for future applications, where the movement of the electrons is crucial.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Donator−Acceptor Map and Work Function for Linear Polyene-Conjugated Molecules. A Density Functional Approximation Study

Martı́nez

2009

J. Phys. Chem. B

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“…As supported by previous UPS work, − , the Mg−Alq 3 complex is likely to have an energy level in the gap between the LUMO of the bulk Alq 3 film and the Mg Fermi level. Graphitic carbon could also possess energy states in this gap region because its work function is known to be lower than that of Mg and subject to mediation by the presence of metallic impurities . These gap states could serve as intermediate states for electron injection from the metal Fermi level to the Alq 3 LUMO, thereby lowering the energy required for this process. , The presence of both reaction products and decomposition products is also likely to create disorder within the interface that would further broaden interfacial state energies and lower the energy required for electron injection.…”

Section: Discussionmentioning

confidence: 99%

Surface Raman Spectroscopy of the Interface of Tris-(8-hydroxyquinoline) Aluminum with Mg

Davis

Pemberton

2009

J. Am. Chem. Soc.

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Surface Raman spectroscopy in ultrahigh vacuum is used to interrogate interfaces formed between tris-(8-hydroxyquinoline) aluminum (Alq(3)) and vapor-deposited Mg. The Raman spectral results for deposition of Mg mass thicknesses between 5 and 20 A indicate formation of a complex interfacial region composed primarily of Mg-Alq(3) adducts and small-grained amorphous or nanocrystalline graphite, the presence of which may have a significant effect on the electronic properties of this metal-organic interface. The observed shifts in nu(ring), nu(C-N), nu(Al-N), and nu(Al-O) modes along with the appearance of nu(Mg-C) and nu(Mg-O) modes suggest a structure for the Mg-Alq(3) adduct in which Mg is bound to the O and C atoms of Alq(3). In addition, several intense, broad modes are observed that are consistent with partial graphitization of the Alq(3) film.

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“…Combining the effects both from carbon core and surface functional groups, the equations may be written as and For graphite, the effective masses of electron and hole are 0.09 and 0.11 m 0 , respectively . As the work function of graphite is −3.93 ± 0.19 eV and that of graphene is −4.30 ± 0.05 eV, we adopted −4.11 eV (mean value of them) as the value of E WF in our calculation. The values of D / A for surface functional groups C–COOH, C–OH, and C–H are calculated to be 0.159, −0.115, and −0.037 eV, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…For graphite, the effective masses of electron and hole are 0.09 and 0.11 m 0 , respectively. 25 As the work function of graphite is −3.93 ± 0.19 eV 26 and that of graphene is −4.30 ± 0.05 eV, 27 we adopted…”

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confidence: 99%

Simple Semiempirical Method for the Location Determination of HOMO and LUMO of Carbon Dots

et al. 2021

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Carbon dots (C-Dots) have many unique properties, which endow them with a promising platform from catalysis to biology applications. However, quantitative understanding of those properties of C-Dots is still a tremendous challenge, and thus an urgent task is to develop a simple theoretical prediction method to quantitatively determine the energy levels of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) by a simple equation. Here, we determine the energy levels of LUMO and HOMO of C-Dots using the tight-binding method as well as the adjustment from the surface functional groups. A quantitative linear relationship between HOMO and HOMO–LUMO gap of C-Dots was obtained, which allows us to deeply understand the optical and photoelectrochemical properties.

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Investigations concerning the work function of doped graphite

Cited by 9 publications

References 4 publications

Donator−Acceptor Map and Work Function for Linear Polyene-Conjugated Molecules. A Density Functional Approximation Study

Donator−Acceptor Map and Work Function for Linear Polyene-Conjugated Molecules. A Density Functional Approximation Study

Surface Raman Spectroscopy of the Interface of Tris-(8-hydroxyquinoline) Aluminum with Mg

Simple Semiempirical Method for the Location Determination of HOMO and LUMO of Carbon Dots

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