Nucleation and Growth of Thin Pentacene Films Studied by LEEM and STM

Sadowski, Jerzy; Abdullah, Amir; Fujikawa, Y.; Sakurai, Takeshi

doi:10.1007/978-3-540-77968-1_20

Cited by 3 publications

(2 citation statements)

References 49 publications

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“…On the one hand, the interaction between Tc or Pc and H/Si(111) is expected to be weak [24][25][26][27][28]. On the other hand, the unit cell lattice parameters for islands, monolayers and thin films of both Pc on H/Si(111) [25,26,29,30] and Pc and Tc at other weakly interacting surfaces [28,[31][32][33][34][35][36][37][38][39][40][41] do not match the unit cell lattice parameter expected [42] for H/Si(111) well. As a result [43], large low-strain commensurate approximate unit cells are necessary, leading to slab models of the interface with hundreds of atoms or more.…”

Section: Introductionmentioning

confidence: 93%

Pentacene and tetracene molecules and films on H/Si(111): level alignment from hybrid density functional theory

Janke¹,

Rossi²,

Levchenko³

et al. 2020

Electron. Struct.

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The electronic properties of hybrid organic-inorganic semiconductor interfaces depend strongly on the alignment of the electronic carrier levels in the organic/inorganic components. In the present work, we address this energy level alignment from first principles theory for two paradigmatic organic-inorganic semiconductor interfaces, the singlet fission materials tetracene and pentacene on H/Si(111), using all-electron density functional theory calculations with a hybrid exchange-correlation functional. For isolated tetracene on H/Si(111), a type I-like heterojunction (lowest-energy electron and hole states on Si) is found. For isolated pentacene, the molecular and semiconductor valence band edges are degenerate. For monolayer films, we show how to construct supercell geometries with up to 1192 atoms, which minimize the strain between the inorganic surface and an organic monolayer film. Based on these models, we predict the formation of type II heterojunctions (electron states on Si, hole-like states on the organic species) for both acenes, indicating that charge separation at the interface between the organic and inorganic components is favored. The paper discusses the steps needed to find appropriate low-energy interface geometries for weakly bonded organic molecules and films on inorganic substrates from first principles, a necessary prerequisite for any computational level alignment prediction.

show abstract

Section: Introductionmentioning

confidence: 93%

Pentacene and tetracene molecules and films on H/Si(111): level alignment from hybrid density functional theory

Janke¹,

Rossi²,

Levchenko³

et al. 2020

Electron. Struct.

View full text Add to dashboard Cite

show abstract

“…On the one hand, the interaction between Tc or Pc and H/Si (111) is weak, as evidenced [27] by the observed lack of a wetting layer [28] and the standing in-plane (herringbone) orientation of Pc [29] and Tc [30,31] molecules around room temperature in thin films and islands on surfaces like H/Si (111). On the other hand, the unit cell lattice parameters for islands, monolayers and thin films of both Pc on H/Si (111) [29,32,28,33] and Pc and Tc at other weakly interacting surfaces [34,35,31,36,37,38,39,40,30,41,42,43,44] do not match the unit cell lattice parameter expected [45] for H/Si (111) well. As a result [46], large low-strain commensurate approximate unit cells are necessary, leading to slab models of the interface with hundreds of atoms or more.…”

Section: Introductionmentioning

confidence: 99%

Pentacene and Tetracene Molecules and Films on H/Si(111): Level Alignment from Hybrid Density Functional Theory

Janke¹,

Rossi²,

Levchenko³

et al. 2020

Preprint

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The electronic properties of hybrid organic-inorganic semiconductor interfaces depend strongly on the alignment of the electronic carrier levels in the organic/inorganic components. In the present work, we address this energy level alignment from first principles theory for two paradigmatic organic-inorganic semiconductor interfaces, the singlet fission materials tetracene and pentacene on H/Si(111), using all-electron hybrid density functional theory. For isolated tetracene on H/Si(111), a type I-like heterojunction (lowest-energy electron and hole states on Si) is found. For isolated pentacene, the molecular and semiconductor valence band edges are degenerate. For monolayer films, we show how to construct supercell geometries with up to 1,192 atoms, which minimize the strain between the inorganic surface and an organic monolayer film. Based on these models, we predict the formation of type II heterojunctions (electron states on Si, hole-like states on the organic species) for both acenes, indicating that charge separation at the interface between the organic and inorganic components is favored. The paper discusses the steps needed to find appropriate low-energy interface geometries for weakly bonded organic molecules and films on inorganic substrates from first principles, a necessary prerequisite for any computational level alignment prediction.

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Real‐Time Microscopy of Reorientation Driven Nucleation and Growth in Pentacene Thin Films on Silicon Dioxide

Abdullah

Fujikawa

Sakurai

et al. 2013

Adv Funct Materials

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The role of molecular reorientation processes in the self‐assembly of anisotropic molecules, such as pentacene (Pn) is studied utilizing a unique capability of low‐energy electron microscopy (LEEM) for the real‐time investigation of the film growth. In Pn film on SiO2, a layer‐by‐layer growth is observed, albeit different from the expected Volmer–Weber growth mode typical for the systems with lower adhesion (weak interfacial interaction). The observed growth mechanism is also different than conventional concept of layer‐by‐layer, or Frank van der Merwe growth. In the Pn/SiO2 system the nucleation density decreases in each consecutive layer, at least up to four monolayers. This growth mechanism is hereafter named inverse Stranski‐Krastanov growth. Furthermore, in this growth system the second layer islands nucleate preferentially at the domain boundaries formed by the interconnections of the bottom (first layer) domains. The top layer overgrows bottom layer with its own, initial in‐plane crystal orientation, regardless of the in‐plane orientations in underlying Pn domains. The dark‐field LEEM imaging allows us to distinguish between Pn domains having different azimuthal direction of molecular tilt. LEEM intensity versus start voltage (LEEM I–V) curves taken in the vicinity of mirror potential from the first and second layer Pn islands show that the surface potential of the second layer is higher by about 0.05 eV than that of the first layer, while the surface potentials for the epitaxial and non‐epitaxial parts of the second layer island are identical.

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Nucleation and Growth of Thin Pentacene Films Studied by LEEM and STM

Cited by 3 publications

References 49 publications

Pentacene and tetracene molecules and films on H/Si(111): level alignment from hybrid density functional theory

Pentacene and tetracene molecules and films on H/Si(111): level alignment from hybrid density functional theory

Pentacene and Tetracene Molecules and Films on H/Si(111): Level Alignment from Hybrid Density Functional Theory

Real‐Time Microscopy of Reorientation Driven Nucleation and Growth in Pentacene Thin Films on Silicon Dioxide

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