Defect contributions to conductivity in poly(3-hexylthiophene)?

Authors

A. N. Caruso, North Dakota State UniversityFollow
D.-Q. Feng, University of Nebraska-Lincoln
Yaroslav B. Losovyj, Louisiana State University at Baton RougeFollow
D. L. Schulz, North Dakota State University
Snjezana Balaz, University of Nebraska-LincolnFollow
Luis G. Rosa, University of Nebraska-LincolnFollow
Andrei Sokolov, University of Nebraska-LincolnFollow
Bernard Doudin, University of Nebraska-LincolnFollow
Peter A. Dowben, University of Nebraska-LincolnFollow

Date of this Version

3-1-2006

Comments

Published in physica status solidi (b) 243, No. 6 (2006), pp. 1321–1330; doi 10.1002/pssb.200541257. Copyright © 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Used by permission.

Abstract

We find evidence for a gradual change in the electronic properties of spin coated poly(3-hexylthiophene) thin films with temperature. The conduction properties appears to be mediated by hopping conduction dominated by a low density of defects states within the highest occupied molecular orbital to lowest unoccupied molecular orbital gap, not by a change in band gap. The photoemission and transport measurements indicate a loss of charge mobility or carrier concentration occurs with decreasing temperature, while the molecular configuration (through chain conjugation) also changes with temperature. The defects states identified by photoemission (–1.7 eV) as well as others contributing to the transport properties are believed to be very heterogeneous along the polymer backbone.