Highly Ordered Single Domain Peri-Tetracene Monolayers on Ag(110).

Area of Science:

• Surface science
• Organic chemistry
• Materials science

Background:

• 1,1′-bitetracene (Bi4A) is a precursor molecule for larger polycyclic aromatic hydrocarbons.
• On-surface synthesis offers a pathway to create complex organic structures with tailored electronic properties.
• Understanding molecule-substrate interactions is crucial for controlling self-assembly and material properties.

Purpose of the Study:

• To investigate the on-surface reaction of 1,1′-bitetracene (Bi4A) to peri-tetracene (4-PA) on Cu(110) and Ag(110) surfaces.
• To explore the potential for forming large-area, ordered 4-PA monolayers.
• To elucidate the electronic interactions between 4-PA molecules and the metal substrates.

Main Methods:

• Photoemission spectroscopy
• Scanning tunneling microscopy (STM)
• Low energy electron diffraction (LEED)
• Density functional theory (DFT) computations

Main Results:

• The transformation of Bi4A to 4-PA was confirmed on both Cu(110) and Ag(110).
• Ag(110) promotes the formation of large-area, highly ordered 4-PA monolayers with preferential molecular alignment along the [11̅0] direction.
• Two distinct 4-PA phases were observed, forming seamlessly over large areas and across step edges.
• Evidence of charge transfer from the Ag(110) substrate to 4-PA molecules was detected, leading to the filling of the lowest unoccupied molecular orbital (LUMO).

Conclusions:

• Ag(110) is a suitable substrate for the synthesis of large-area, ordered peri-tetracene monolayers.
• The observed charge transfer influences the electronic properties of the 4-PA molecules.
• On-surface synthesis provides a route to precisely engineer organic electronic materials.