Carrier dynamics in α-octithiophene (8T) solids: comparison of the transient photoconductivity and photoinduced absorption in single crystals and polycrystalline films

D. Moses, J. Wang, A. Dogariu, D. Fichou, C. Videlot

Research output: Contribution to journalConference article

1 Scopus citations

Abstract

We demonstrate that the properties of the transient photoconductivity such as its life time and its dependence on light intensity and electric field (E) in crystal 8T are radically different from those in 8T oriented polycrystalline film. Our observations indicate a bimolecular carrier recombination mechanism prevailing in the 8T crystal, whereas a mono-molecular one operates in the polycrystalline film. The role of the structural defects in the 8T film on the transport is revealed by the deviation from the ohmic behavior seen in the 8T crystals into a sublinear dependence of the photocurrent on E in the polycrystalline film. Our studies reveal relative high photoluminescence (PL) efficiency and amplified spontaneous emission (ASE) but very small photoinduced absorption (PA) in the 8T crystal, in contrast to a much smaller PL, broader emission that extends to the near IR, and much higher PA, leading to the absence of stimulated emission (SE) in the 8T polycrystalline film. This indicates that disorder in the 8T system introduces new states that allow for radiative transitions in the near IR region as well as higher transition probability that results in increased PA in the 8T polycrystalline film.

Original languageEnglish (US)
Pages (from-to)421-424
Number of pages4
JournalSynthetic Metals
Volume101
Issue number1
DOIs
StatePublished - May 1999
Externally publishedYes
EventProceedings of the 1998 International Conference on Science and Technology of Synthetic Metals (ICSM-98) - Montpellier
Duration: Jul 12 1998Jul 18 1998

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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