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Title: Frequency-dependent photothermal measurement of transverse thermal diffusivity of organic semiconductors

Abstract

We have used a photothermal technique, in which chopped light heats the front surface of a small (∼1 mm{sup 2}) sample and the chopping frequency dependence of thermal radiation from the back surface is measured with a liquid-nitrogen-cooled infrared detector. In our system, the sample is placed directly in front of the detector within its dewar. Because the detector is also sensitive to some of the incident light, which leaks around or through the sample, measurements are made for the detector signal that is in quadrature with the chopped light. Results are presented for layered crystals of semiconducting 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pn) and for papers of cellulose nanofibrils coated with semiconducting poly(3,4-ethylene-dioxythiophene):poly(styrene-sulfonate) (NFC-PEDOT). For NFC-PEDOT, we have found that the transverse diffusivity, smaller than the in-plane value, varies inversely with thickness, suggesting that texturing of the papers varies with thickness. For TIPS-pn, we have found that the interlayer diffusivity is an order of magnitude larger than the in-plane value, consistent with previous estimates, suggesting that low-frequency optical phonons, presumably associated with librations in the TIPS side groups, carry most of the heat.

Authors:
; ;  [1]; ;  [2]; ;  [3]
  1. Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506-0055 (United States)
  2. Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055 (United States)
  3. Department of Science and Technology, Organic Electronics, Linköping University, SE-601 74 Norrköping (Sweden)
Publication Date:
OSTI Identifier:
22493075
Resource Type:
Journal Article
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 118; Journal Issue: 23; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-8979
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CELLULOSE; CRYSTALS; DEWARS; FREQUENCY DEPENDENCE; INFRARED THERMOGRAPHY; NANOFIBERS; ORGANIC SEMICONDUCTORS; PENTACENE; PHONONS; SIGNALS; STYRENE; THERMAL DIFFUSIVITY; THERMAL RADIATION; VISIBLE RADIATION

Citation Formats

Brill, J. W., Shahi, Maryam, Yao, Y., Payne, Marcia M., Anthony, J. E., Edberg, Jesper, and Crispin, Xavier. Frequency-dependent photothermal measurement of transverse thermal diffusivity of organic semiconductors. United States: N. p., 2015. Web. doi:10.1063/1.4937565.
Brill, J. W., Shahi, Maryam, Yao, Y., Payne, Marcia M., Anthony, J. E., Edberg, Jesper, & Crispin, Xavier. Frequency-dependent photothermal measurement of transverse thermal diffusivity of organic semiconductors. United States. https://doi.org/10.1063/1.4937565
Brill, J. W., Shahi, Maryam, Yao, Y., Payne, Marcia M., Anthony, J. E., Edberg, Jesper, and Crispin, Xavier. 2015. "Frequency-dependent photothermal measurement of transverse thermal diffusivity of organic semiconductors". United States. https://doi.org/10.1063/1.4937565.
@article{osti_22493075,
title = {Frequency-dependent photothermal measurement of transverse thermal diffusivity of organic semiconductors},
author = {Brill, J. W. and Shahi, Maryam and Yao, Y. and Payne, Marcia M. and Anthony, J. E. and Edberg, Jesper and Crispin, Xavier},
abstractNote = {We have used a photothermal technique, in which chopped light heats the front surface of a small (∼1 mm{sup 2}) sample and the chopping frequency dependence of thermal radiation from the back surface is measured with a liquid-nitrogen-cooled infrared detector. In our system, the sample is placed directly in front of the detector within its dewar. Because the detector is also sensitive to some of the incident light, which leaks around or through the sample, measurements are made for the detector signal that is in quadrature with the chopped light. Results are presented for layered crystals of semiconducting 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pn) and for papers of cellulose nanofibrils coated with semiconducting poly(3,4-ethylene-dioxythiophene):poly(styrene-sulfonate) (NFC-PEDOT). For NFC-PEDOT, we have found that the transverse diffusivity, smaller than the in-plane value, varies inversely with thickness, suggesting that texturing of the papers varies with thickness. For TIPS-pn, we have found that the interlayer diffusivity is an order of magnitude larger than the in-plane value, consistent with previous estimates, suggesting that low-frequency optical phonons, presumably associated with librations in the TIPS side groups, carry most of the heat.},
doi = {10.1063/1.4937565},
url = {https://www.osti.gov/biblio/22493075}, journal = {Journal of Applied Physics},
issn = {0021-8979},
number = 23,
volume = 118,
place = {United States},
year = {Mon Dec 21 00:00:00 EST 2015},
month = {Mon Dec 21 00:00:00 EST 2015}
}