Critical interface properties of metalorganic species of technological and fundamental importance.
EMSL Project ID
44621
Abstract
This project focuses on in depth fundamental understanding of the interfaces of metalorganic films. As a model for porphyrins, phthalocyanines, and other technologically important metalorganics, we will use naphthalocyanines (Nc). Generally these complexes are p-type semiconductors having a band gap of the order of 1.5 eV, but they can be tuned by fluorine substitution to be n-type. They have tremendous potential applications in sensors, OLEDs, organic FETs, and other organic based electronic devices. Our focus will be on the metal-metalorganic interface that is a critical interface in OLED and FET devices, and upon the metalorganic-reactive vapor interface that is essential for sensor operation. Low energy electron diffraction (LEED) and scanning tunneling microscopy (STM) will be used to determine the structure of species at the interface and in add layers as the film grows towards bulk structure. Orbital mediated tunneling spectroscopy (OMTS) and inelastic electron tunneling spectroscopy (IETS) will be used to characterize the electronic and vibrational structure over the same range of metalorganic film thickness. Once the interface with the electrical contact (metal layer) is understood, we will investigate the role of adduct formation between various metalorganics and reactive species such as NO and NH3. Of particular interest will be the adduct structure and the identification of the electronic and vibrational states of the overall adduct. Both the need for high spatial stability (in order to precisely assign electronic and vibrational states to particular atomic regions of the metalorganic) and high spectral resolution (in order to observe vibronic structuring on OMTS and to identify similar vibrational transition) require the use of a low temperature STM in which the entire microscope is cooled. The new low-T STM at EMSL is ideal for this work and a similar system is not available to us. These experiments will be paired with ab initio calculations of metalorganics adsorbed on small Au and Cu islands representative of single crystal surfaces. While we have access to a small system which we use for DFT calculations on free molecules and in continuum solvents, the surface modeling proposed here will require the much more powerful Chinook system. The results of these studies will have immediate application to the surface chemistry of metalorganic systems. They will provide important fundamental knowledge relating to chemical sensors and to a broad class of materials used in organic electronics. Moreover, they will contribute to our fundamental understanding of inelastic and elastic tunneling events.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2011-10-01
End Date
2014-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Chilukuri B, U Mazur, and KW Hipps. 2014. "Effect of Dispersion on Surface Interactions of Cobalt(II) Octaethylporphyrin Monolayer on Au(111) and HOPG(0001) Substrates: a Comparative First Principles Study ." Physical Chemistry Chemical Physics. PCCP 16:14096-14107. doi: 10.1039/C4CP01762E
Eskelsen JR, Y Qi, S Schneider-Pollack, S Schmitt, KW Hipps, and U Mazur. 2014. "Correlating Elastic Properties and Molecular Organization of an Ionic Organic Nanostructure." Nanoscale 6(1):316-327. doi:10.1039/C3NR05047E
Mereghetti P, RC Wade, and M Martinez. 2014. "Long Range Debye-Hückel Correction for Computation of Grid-based Electrostatic Forces Between Biomacromolecules." BMC Biophysics 7(4):, doi:10.1186/2046-1682-7-4
Wiggins BC, and KW Hipps. 2014. "Investigation of Metal Free Naphthalocyanine Vapor Deposited on Au(111)." Journal of Physical Chemistry C 118(8):4222-4230. doi:10.1021/jp4115282