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Title: Molecular weight dependence of carrier mobility and recombination rate in neat P3HT films

Abstract

The microstructure dependence of carrier mobility and recombination rates of neat films of poly 3-hexylthyophene (P3HT) were determined for a range of materials of weight-average molecular weights, Mw, ranging from 14 to 331 kDa. This variation has previously been shown to modify the polymer microstructure, with low molecular weights forming a one-phase, paraffinic-like structure comprised of chain-extended crystallites, and higher molecular weights forming a semicrystalline structure with crystalline domains being embedded in an amorphous matrix. Using Charge Extraction by Linearly Increasing Voltage (CELIV), we show here that the carrier mobility in P3HT devices peaks for materials of Mw = 48 kDa, and that the recombination rate decreases monotonically with increasing molecular weight. This trend is likely due to the development of a semicrystalline, two-phase structure with increasing Mw, which allows for the spatial separation of holes and electrons into the amorphous and crystalline regions, respectively. This separation leads to decreased recombination.

Authors:
ORCiD logo [1];  [1];  [1];  [2];  [3];  [1]
  1. Univ. of Colorado, Boulder, CO (United States)
  2. Imperial College, London (United Kingdom)
  3. National Renewable Energy Lab. (NREL), Golden, CO (United States)
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
OSTI Identifier:
1412831
Report Number(s):
NREL/JA-5900-70633
Journal ID: ISSN 0887-6266
Grant/Contract Number:  
AC36-08GO28308
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Polymer Science. Part B, Polymer Physics
Additional Journal Information:
Journal Volume: 56; Journal Issue: 1; Journal ID: ISSN 0887-6266
Publisher:
Wiley
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; carrier mobility; carrier recombination; CELIV; conjugated polymer; molecular weight; P3HT

Citation Formats

Dixon, Alex G., Visvanathan, Rayshan, Clark, Noel A., Stingelin, Natalie, Kopidakis, Nikos, and Shaheen, Sean E. Molecular weight dependence of carrier mobility and recombination rate in neat P3HT films. United States: N. p., 2017. Web. doi:10.1002/polb.24531.
Dixon, Alex G., Visvanathan, Rayshan, Clark, Noel A., Stingelin, Natalie, Kopidakis, Nikos, & Shaheen, Sean E. Molecular weight dependence of carrier mobility and recombination rate in neat P3HT films. United States. doi:10.1002/polb.24531.
Dixon, Alex G., Visvanathan, Rayshan, Clark, Noel A., Stingelin, Natalie, Kopidakis, Nikos, and Shaheen, Sean E. Thu . "Molecular weight dependence of carrier mobility and recombination rate in neat P3HT films". United States. doi:10.1002/polb.24531.
@article{osti_1412831,
title = {Molecular weight dependence of carrier mobility and recombination rate in neat P3HT films},
author = {Dixon, Alex G. and Visvanathan, Rayshan and Clark, Noel A. and Stingelin, Natalie and Kopidakis, Nikos and Shaheen, Sean E.},
abstractNote = {The microstructure dependence of carrier mobility and recombination rates of neat films of poly 3-hexylthyophene (P3HT) were determined for a range of materials of weight-average molecular weights, Mw, ranging from 14 to 331 kDa. This variation has previously been shown to modify the polymer microstructure, with low molecular weights forming a one-phase, paraffinic-like structure comprised of chain-extended crystallites, and higher molecular weights forming a semicrystalline structure with crystalline domains being embedded in an amorphous matrix. Using Charge Extraction by Linearly Increasing Voltage (CELIV), we show here that the carrier mobility in P3HT devices peaks for materials of Mw = 48 kDa, and that the recombination rate decreases monotonically with increasing molecular weight. This trend is likely due to the development of a semicrystalline, two-phase structure with increasing Mw, which allows for the spatial separation of holes and electrons into the amorphous and crystalline regions, respectively. This separation leads to decreased recombination.},
doi = {10.1002/polb.24531},
journal = {Journal of Polymer Science. Part B, Polymer Physics},
number = 1,
volume = 56,
place = {United States},
year = {Thu Nov 02 00:00:00 EDT 2017},
month = {Thu Nov 02 00:00:00 EDT 2017}
}

Journal Article:
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Works referenced in this record:

Dependence of Regioregular Poly(3-hexylthiophene) Film Morphology and Field-Effect Mobility on Molecular Weight
journal, April 2005

  • Kline, R. Joseph; McGehee, Michael D.; Kadnikova, Ekaterina N.
  • Macromolecules, Vol. 38, Issue 8, p. 3312-3319
  • DOI: 10.1021/ma047415f

Conjugated Polymer-Based Organic Solar Cells
journal, April 2007

  • Günes, Serap; Neugebauer, Helmut; Sariciftci, Niyazi Serdar
  • Chemical Reviews, Vol. 107, Issue 4, p. 1324-1338
  • DOI: 10.1021/cr050149z