Mapping the electronic structure of polypyrrole with image-based electrochemical scanning tunneling spectroscopy
Abstract: Conducting polymers are semiconductors whose applications cover a wide range of devices. Their versatility is due, in addition to other factors, to properties that can be easily modulated according to the intended application. It is therefore important to study and map the electronic structure of these materials for a better correlation between structure and properties. Electrochemical scanning tunneling spectroscopy (EC-STS) can be a powerful tool to characterize the electronic structure of the semiconductor interface. In this work, we have used image-based EC-STS (IB-EC-STS) to describe quantitatively the band structure of an electrochemically deposited polypyrrole film. IB-EC-STS located the band edge of the polymer’s valence band (VB) at 0.95 V vs. RHE (-5.33 eV in the absolute potential scale) and the intragap polaron states formed when the polymer is doped, at 0.46 V vs. RHE (-4.84 eV). The IB-EC-STS data were cross-checked with electrochemical impedance spectroscopy (EIS) and Mott-Schottky analysis of the interfacial capacitance. The DOS spectrum obtained from EIS data is consistent with the STS-deduced location of the VB and the polarons.
Author(s): Gonçalves, R.; Paiva, R.S.; Ramírez, A.M.R. ; Mwanda, J.A.; Pereira, E.C.; Cuesta, A.
Electrochemical Science Advances
Published: 04 May 2021, Volume2, Issue2
DOI: https://doi.org/10.1002/elsa.202100028
CDMF
The CDMF, hosted at the Federal University of São Carlos (UFSCar), is one of the Research, Innovation and Dissemination Centers (RIDC) supported by the São Paulo State Research Support Foundation (Fapesp), and also receives investment from the National Council Scientific and Technological Development (CNPq), from the National Institute of Science and Technology of Materials in Nanotechnology (INCTMN).
