skip to main content

SciTech ConnectSciTech Connect

Title: Energy resolved electrochemical impedance spectroscopy for electronic structure mapping in organic semiconductors

We introduce an energy resolved electrochemical impedance spectroscopy method to map the electronic density of states (DOS) in organic semiconductor materials. The method consists in measurement of the charge transfer resistance of a semiconductor/electrolyte interface at a frequency where the redox reactions determine the real component of the impedance. The charge transfer resistance value provides direct information about the electronic DOS at the energy given by the electrochemical potential of the electrolyte, which can be adjusted using an external voltage. A simple theory for experimental data evaluation is proposed, along with an explanation of the corresponding experimental conditions. The method allows mapping over unprecedentedly wide energy and DOS ranges. Also, important DOS parameters can be determined directly from the raw experimental data without the lengthy analysis required in other techniques. The potential of the proposed method is illustrated by tracing weak bond defect states induced by ultraviolet treatment above the highest occupied molecular orbital in a prototypical σ-conjugated polymer, poly[methyl(phenyl)silylene]. The results agree well with those of our previous DOS reconstruction by post-transient space-charge-limited-current spectroscopy, which was, however, limited to a narrow energy range. In addition, good agreement of the DOS values measured on two common π-conjugated organic polymer semiconductors,more » polyphenylene vinylene and poly(3-hexylthiophene), with the rather rare previously published data demonstrate the accuracy of the proposed method.« less
Authors:
;  [1] ;  [2] ;  [3]
  1. Institute of Physics SAS, Dúbravská cesta 9, 845 11 Bratislava (Slovakia)
  2. Faculty of Education, Trnava University in Trnava, 918 43 Trnava (Slovakia)
  3. (Czech Republic)
Publication Date:
OSTI Identifier:
22350854
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 14; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ACCURACY; CRYSTAL DEFECTS; CURRENTS; DENSITY; ELECTRIC POTENTIAL; ELECTROCHEMISTRY; ELECTROLYTES; ELECTRONIC STRUCTURE; IMPEDANCE; INTERFACES; MOLECULAR ORBITAL METHOD; ORGANIC POLYMERS; ORGANIC SEMICONDUCTORS; REDOX REACTIONS; SPACE CHARGE; SPECTROSCOPY; TRANSIENTS; ULTRAVIOLET RADIATION