Phenazine Cation Radical Salts: Charge‐transfer Complexes With Tcnq*

Soos, Z. G.; Keller, Heimo J.; Moroni, W.; Nöthe, D.

doi:10.1111/j.1749-6632.1978.tb39437.x

Cited by 42 publications

(34 citation statements)

References 29 publications

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“…According to | ψ ( θ )〉 in Equation 1, the CT model is limited to the singly occupied orbital of an adsorbed ion radical. CT models of condensed phases10–13 emphasize electron correlation in systems with small t , while all electrons and overlaps are considered in direct calculations that are typically less correlated. There is no sharp separation between CT and polarization, either.…”

Section: Discussionmentioning

confidence: 99%

“…The optical, magnetic and electrical properties of CT and radical ion salts have been extensively discussed in term of small t in face‐to‐face stacks with separation slightly below the van der Waals radius of conjugated molecules. Small t is sufficient for collective effects such as neutral–ionic transitions or crossovers in CT crystals10, 11 or molecular aggregates 12, 13. Collective effects are particularly important when the neutral and ionic states are almost degenerate.…”

Section: Introductionmentioning

confidence: 99%

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Profiles of Work Function Shifts and Collective Charge Transfer in Submonolayer Metal–Organic Films

Topham

Kumar

Soos

2011

Adv Funct Materials

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Vacuum level shifts Δ ( d ) at metal-organic (m-O) interfaces indicate the formation of surface dipoles for fi lm thickness d ≤ ≤ d ML up to a monolayer (ML). Shifts or profi les Δ ( θ ) of submonolayer fi lms are nonlinear in the coverage θ = d / d ML ≤ ≤ 1, which points to cooperative interactions between adsorbed molecules. Adsorption with weak nonspecifi c bonding is modeled as charge transfer (CT) between molecules M and localized surface states S of the metal. The dipole μ 0 of ions S − M + or S + M − gives upper bounds for the vacuum level shift Φ 0 and dipole-dipole repulsion V 0 at θ = 1. Partial CT ρ ( θ ) < 1 is found self consistently and accounts for published profi les Δ ( θ ) of representative planar and nonplanar molecules with d ML ∼ 4 and ∼ 10 Å. Initial adsorption at θ ∼ 0 has considerable ionic character, ρ (0) ∼ 1/2, that decreases to ρ (1) ∼ 1/10 at θ = 1. Planar molecules with small μ 0 and V 0 have slightly nonlinear profi les while molecules with large μ 0 and V 0 have highly nonlinear Δ ( θ ). Collective CT is a phenomenological model for m-O interfaces with nonspecifi c bonding. The CT model is contrasted to fi xed dipoles on the surface, to calculations of Δ (1) and to simulations of sub-ML fi lms.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Profiles of Work Function Shifts and Collective Charge Transfer in Submonolayer Metal–Organic Films

Topham

Kumar

Soos

2011

Adv Funct Materials

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“…Collective CT refers to the self-consistent treatment of dimers on an infinite surface. We follow previous CT studies of organic crystals 14,15 or molecular aggregates. 16,17 The energies of the two states are E(AS) and E(A -S + ) when the CT integral is t = 0.…”

Section: Recent Interest In F4tcnqmentioning

confidence: 99%

“…Direct evaluation Γ(0) or t requires explicit consideration of both molecules and surfaces. Related models of ionradical or CT salts 1,14,15 or of molecular aggregates 16,17 Theoretical interest in surface dipoles has focused on the magnitude 13 of Δ, the pillow effect, 28 induced density of interface states 32 and cluster calculations 33 . Some studies have considered both 23,34 θ = 1/2 and θ = 1 or variable 35 θ in sub MLs with constrained structures.…”

mentioning

confidence: 99%

Surface dipole of F4TCNQ films: Collective charge transfer and dipole–dipole repulsion in submonolayers

Soos

Topham

2011

Organic Electronics

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A charge transfer (CT) model is introduced for strong acceptors like A = F4TCNQ that are ionized on surfaces at low coverage θ. Each A forms a CT dimer with a surface state S. Dipole-dipole repulsion grows as θ 3/2 up to θ = 1 in a full monolayer.Electron transfer ρ(θ) within dimers is found self-consistently and decreases with increasing coverage. The surface dipole and work function shift ΔΦ are proportional to θρ(θ). The CT model has implications for photoemission and accounts for ΔΦ(d) profiles of F4TCNQ films of thickness d on Cu(1,1,1) or on hydrogenated diamond (1,0,0). The CT model also describes ΔΦ(θ) of organic donors on metals and is contrasted to previous treatments of dipoles on a surface.

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“…5 However, extensive experimental studies of these systems in the early eighties led to the development of a theoretical model that allows a degree of ionicity different from zero or one. 6,7 Furthermore, one of the essential requirements so that the segregated CT complexes yield high conductivity is that the charge transfer from donors to acceptors be incomplete. Therefore, attention has focused on obtaining an estimate for this quantity.…”

Section: Introductionmentioning

confidence: 99%

First-principles molecular-dynamics simulations for neutralp-chloranil and its radical anion

et al. 1996

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The neutral p-chloranil ͑2,3,5,6-tetrachloro-p-benzoquinone͒ and its radical anion have been extensively studied using the Car-Parrinello projector augmented wave method, which is an all-electron electronic structure method for first-principles molecular dynamics based on the local density approximation of density functional theory. Frequencies and eigenmodes are derived by fitting a system of harmonic oscillators to the moleculardynamics trajectories. The dependence of the bond lengths and vibrational frequencies on the molecular ionicity is discussed, and the electron affinity, Coulomb repulsion, and the spin-splitting parameter of p-chloranil are also derived. ͓S0163-1829͑96͒05318-0͔

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Phenazine Cation Radical Salts: Charge‐transfer Complexes With Tcnq*

Cited by 42 publications

References 29 publications

Profiles of Work Function Shifts and Collective Charge Transfer in Submonolayer Metal–Organic Films

Profiles of Work Function Shifts and Collective Charge Transfer in Submonolayer Metal–Organic Films

Surface dipole of F4TCNQ films: Collective charge transfer and dipole–dipole repulsion in submonolayers

First-principles molecular-dynamics simulations for neutralp-chloranil and its radical anion

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