Spectroscopy of chemically- and gate-doped carbon nanotubes at the ensemble and single particle level

• Applicant: Professor Dr. Tobias Hertel
• Subject Area: Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry
• Term: from 2016 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 315402952

Doping of semiconductors by the introduction or removal of charges can be used for controlling their electronic and optical structure. This offers many opportunities for the fabrication of versatile materials with new properties, essentially because any semiconductor attribute or phenomenon such as conductivity, energy transport and dissipation, as well as their ability to detect and emit light are affected by charge carrier concentrations. The micro- and nanoelectronic revolution of the past 50 years, for example, would not have been possible without a fundamental understanding of semiconductor doping. Similarly, the doping of nanoscale semiconductors plays a key role for the development of future technologies but is not nearly as well understood or matured. In particular the control and spectroscopic assessment of the doping of one-dimensional semiconductors is sometimes still in its infancy.Within the proposed research project we will seize the opportunity presented by recent advances with the fabrication of pure semiconducting carbon nanotube (s-SWNTs) samples and by new spectroscopic developments, for developing a better understanding and greater control of the doping of s-SWNTs.The key objectives of the proposed research aim at A) the development of a robust methodology for the doping of s-SWNTs by chemical and by physical processes, B) the investigation of the sensitivity of different spectroscopic probes for the detection of doping levels, C) a better understanding and possibly elimination of heterogeneity in doped s-SWNTs and D) laying the foundations for quantitative predictions of the effect of doping on the properties of s-SWNTs and other one-dimensional semiconductors.To meet these objectives we will combine recent advances with the preparation of semiconducting s-SWNT samples with new spectroscopic tools for the investigation of doped s-SWNTs at the ensemble and single particle level. In particular we will work toward a better understanding of the characteristics of doping, induced by chemical and by physical means. Chemical doping will here be achieved by covalent as well as non-covalent interactions of s-SWNTs with redoxactive agents while physical doping will be obtained by field-induced control of electrochemical potentials.The results of this research are expected to facilitate future quantitative analysis and utilization of doped s-SWNTs for fundamental research as well as for potential applications.

• DFG Programme: Research Grants