Monolayer and bilayer pentacene on Cu(111)

TL;DR

This study investigates the morphology and electronic properties of monolayer and bilayer pentacene on Cu(111) using STM and STS, revealing new structural phases and layer-dependent electronic characteristics.

Contribution

It reports the discovery of two new monolayer phases of pentacene on Cu(111) and characterizes the electronic differences between layers.

Findings

Identification of a novel 2D herringbone phase

Observation of a 'random-tiling' monolayer structure

Layer-dependent electronic structure variations

Abstract

The morphology and electronic structure of pentacene (Pn) deposited on Cu(111) was studied using scanning tunneling microscopy (STM) and spectroscopy (STS). Deposition of a multilayer followed by annealing to reduce coverage to a monolayer results in the formation of either of two unique phases: a 2D herringbone structure previously unobserved for any linear acene, or a 'random- tiling' structure. Coverage greater than a monolayer promotes the formation of a bilayer phase similar to that observed for Pn/Ag(111). STS shows that the electronic structure of the first layer is strongly modified due to its proximity to the substrate while the second layer exhibits nearly bulk-like electronic structure.