Sharp organic interface of molecular C60 chains and a pentacene derivative SAM on Au(788): A combined STM & DFT study

• Published in: Surface science 2013-12, Vol.618, p.78-82
• Main Authors: Wang, Jun, Tang, Jian-Ming, Larson, Amanda M., Miller, Glen P., Pohl, Karsten
• Format: Article
• Language: English
• Subjects: Bilayer heterojunctions; Buckminsterfullerene; C60; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Density functional theory; Derivatives; Exact sciences and technology; Fullerenes; Monolayers; Pentacene; Pentacene derivative; Photovoltaic cells; Physics; Scanning tunneling microscopy; Self-assembled monolayers; Solar cells
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2013.08.015

Controlling the molecular structure of the donor–acceptor interface is essential to overcoming the efficiency bottleneck in organic photovoltaics. We present a study of self-assembled fullerene (C60) molecular chains on perfectly ordered 6,13-dichloropentacene (DCP) monolayers forming on a vicinal Au(788) surface using scanning tunneling microscopy in conjunction with density functional theory calculations. DCP is a novel pentacene derivative optimized for photovoltaic applications. The molecules form a brick-wall patterned centered rectangular lattice with the long axis parallel to the monatomic steps that separate the 3.9nm wide Au(111) terraces. The strong interaction between the C60 molecules and the gold substrate is well screened by the DCP monolayer. At submonolayer C60 coverage, the fullerene molecules form long parallel chains, 1.1nm apart, with a rectangular arrangement instead of the expected close-packed configuration along the upper step edges. The perfectly ordered DCP structure is unaffected by the C60 chain formation. The controlled sharp highly-ordered organic interface has the potential to improve the conversion efficiency in organic photovoltaics. Sharp organic interface of molecular C60 chains and a pentacene derivative SAM on Au(788): A combined STM & DFT study [Display omitted] •STM/DFT characterizes C60 and 6,13-dichloropentacene (DCP) co‐assembly on Au(788).•Pentacene derivative, optimized for photovoltaics, forms long-range ordered SAM.•C60 fullerenes form parallel molecular chains on-top intact DCP SAM.•C60 chains adsorb on the upper step edges of DCP covered Au(111) terraces.•DFT predicts charge transfer and dipole moment of the sharp C60‐DCP interface.