Ordered Growth and Electronic Properties of 1,2:8,9-Dibenzopentacene (trans-DBPen) on Ag(111)

Abstract

Herein, we have studied highly ordered two-dimensional layers of 1,2:8,9-dibenzopentacene (trans-DBPen) adsorbed on a single-crystalline silver surface. While its parent molecule pentacene is known for a relatively high hole mobility, reports on trans-DBPen are rather scarce. Furthermore, it belongs to polycyclic aromatic hydrocarbons for which superconducting properties have been observed upon intercalation with potassium. Our scanning tunneling microscopy and low-energy electron diffraction results reveal a highly ordered monolayer structure of trans-DBPen on Ag(111). We further used angle-resolved ultraviolet photoelectron spectroscopy to measure photoelectron momentum maps (PMMs). The experimental PMMs agree very nicely with simulations based on our structural data while assuming free molecules for the density functional theory calculations. A comparison with pentacene yields some insights into the properties of the two related molecules. We conclude that the degree of hybridization between the molecular orbitals and substrate states is comparatively weak. These results are expected to serve as a starting point for future investigations of K-doped monolayers of trans-DBPen.

A Practical General Method for the Preparation of Long Acenes

“…Dibenzopentacenes (DBPen) have been extensively studied both theoretically and experimentally (in the case of trans ‐DBPen) for their potential uses in organic electronics . This interest has been renewed by the discovery of superconductivity of trans ‐DBPen doped with alkali metals with a high critical temperature of 33.1 K .…”

“…However, these results have not been reproduced and remain controversial . One explanation could be that the known synthesis of 3 ( 4 has not yet been described) leads to crude products that require multiple train‐sublimation purifications so that the exact superconductive phase from cruse trans ‐DBPen remains unknown…”

“…Dibenzopentacenes( DBPen) have been extensively studied both theoretically and experimentally (in the case of trans-DBPen) for their potential usesi norganic electronics. [43] This interest has been renewed by the discoveryo fs uperconductivity of trans-DBPen doped with alkali metals with ah ighc ritical temperature of 33.1 K. [44] However,t heser esults have not been reproduced andr emain controversial. [45,46] One explanation could be that the known synthesis of 3 (4 has not yet been described) leads to crude products that require multiple train-sublimation purifications [43] so that the exact superconductive phase from cruse trans-DBPen remains unknown By following the route described in Scheme2with 1,2-naphtyne in place of 2,3-naphthyne, we have obtained dibenzo[a,l]pentacene 3 (trans-DBPen)a nd dibenzo[a,n]pentacene 4 (cis-DBPen) as shown in Scheme 3.…”

“…[43] This interest has been renewed by the discoveryo fs uperconductivity of trans-DBPen doped with alkali metals with ah ighc ritical temperature of 33.1 K. [44] However,t heser esults have not been reproduced andr emain controversial. [45,46] One explanation could be that the known synthesis of 3 (4 has not yet been described) leads to crude products that require multiple train-sublimation purifications [43] so that the exact superconductive phase from cruse trans-DBPen remains unknown By following the route described in Scheme2with 1,2-naphtyne in place of 2,3-naphthyne, we have obtained dibenzo[a,l]pentacene 3 (trans-DBPen)a nd dibenzo[a,n]pentacene 4 (cis-DBPen) as shown in Scheme 3. Diels-Alder addition of 1 with 1,2-naphthyne, prepared in situ by reaction of 1-(trimethylsilyl)naphthalen-2-yl trifluoromethanesulfonate with CsF in acetonitrile, followed by aromatization using DDQ in refluxingt oluene gave a1 :1 mixture of isomers 8a and 8b in 77 %y ield.…”

GIDVis: a comprehensive software tool for geometry-independent grazing-incidence X-ray diffraction data analysis and pole-figure calculations

“…Such cases are present in samples with large individual crystals hosted at surfaces, thus resulting in poor statistics [ Fig. 1(b)], or epitaxially grown crystallites with a defined in-plane alignment (Haber et al, 2005;Otto et al, 2018) [ Fig. 1(c)].…”