Band-like temperature dependence of mobility in a solution-processed organic semiconductor

Tomo Sakanoue, Henning Sirringhaus

Research output: Contribution to journalArticle

294 Citations (Scopus)

Abstract

The mobility μ of solution-processed organic semiconductorshas improved markedly to room-temperature values of 1-5 cm 2 V -1 s -1. In spite of their growing technological importance, the fundamental open question remains whether charges are localized onto individual molecules or exhibit extended-state band conduction like those in inorganic semiconductors. The high bulk mobility of 100 cm 2 V -1 s -1 at 10 K of some molecular single crystals provides clear evidence that extended-state conduction is possible in van-der-Waals-bonded solids at low temperatures. However, the nature of conduction at room temperature with mobilities close to the Ioffe-Regel limit remains controversial. Here we investigate the origin of an apparent band-like, negative temperature coefficient of the mobility (dμ/dT<0) in spin-coated films of 6,13-bis(triisopropylsilylethynyl)-pentacene. We use optical spectroscopy of gate-induced charge carriers to show that, at low temperature and small lateral electric field, charges become localized onto individual molecules in shallow trap states, but that a moderate lateral electric field is able to detrap them resulting in highly nonlinear, low-temperature transport. The negative temperature coefficient of the mobility at high fields is not due to extended-state conduction but to localized transport limited by thermal lattice fluctuations.

Original languageEnglish
Pages (from-to)736-740
Number of pages5
JournalNature Materials
Volume9
Issue number9
DOIs
Publication statusPublished - 2010 Sep
Externally publishedYes

Fingerprint

Semiconducting organic compounds
organic semiconductors
temperature dependence
Negative temperature coefficient
conduction
Temperature
Electric fields
Molecular crystals
Molecules
electric fields
room temperature
coefficients
Conduction bands
Charge carriers
trucks
molecules
charge carriers
conduction bands
traps
Single crystals

ASJC Scopus subject areas

  • Mechanical Engineering
  • Mechanics of Materials
  • Condensed Matter Physics
  • Materials Science(all)
  • Chemistry(all)

Cite this

Band-like temperature dependence of mobility in a solution-processed organic semiconductor. / Sakanoue, Tomo; Sirringhaus, Henning.

In: Nature Materials, Vol. 9, No. 9, 09.2010, p. 736-740.

Research output: Contribution to journalArticle

Sakanoue, Tomo ; Sirringhaus, Henning. / Band-like temperature dependence of mobility in a solution-processed organic semiconductor. In: Nature Materials. 2010 ; Vol. 9, No. 9. pp. 736-740.
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