skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Helical Poly(5-alkyl-2,3-thiophene)s: Controlled Synthesis and Structure Characterization

Abstract

Whereas Poly(3-alkyl-2,5-thiophene)s (P3AT), with many potential applications, have been extensively investigated, their ortho-connected isomers, poly(5-alkyl-2,3-thiophene)s (P5AT), have never been reported because of the difficulty in their syntheses. We herein present the first synthesis of regioregular P5AT via controlled Suzuki cross-coupling polymerization with PEPPSI-IPr as catalyst, affording the polymers with tunable molecular weight, narrow polydispersity (PDI) and well-defined functional end groups at the gram scale. The helical geometry of P5AT was studied by a combination of NMR, small angle x-ray scattering (SAXS) and scanning tunneling microscopy (STM). Particularly, the single polymer chain of poly(5- 2 butyl-2,3-thiophene) (P5BT) on highly oriented pyrolytic graphite (HOPG) substrates with either M or P helical conformation was directly observed by STM. The comparison of UV-vis absorption between poly(5-hexyl-2,3-thiophene) (P5HT) (λ = 345 nm) and poly(3-hexyl-2,5- thiophene) (P3HT) (λ = 450 nm) indicated that the degree of conjugation of the backbone in P5HT is less than in P3HT, which may be a consequence of the helical geometry of the former compared to the more planar geometry of the latter. Moreover, we found that P5HT can emit green fluorescence under UV (λ = 360 nm) irradiation

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1265664
Grant/Contract Number:
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Macromolecules
Additional Journal Information:
Journal Volume: 49; Journal Issue: 13; Journal ID: ISSN 0024-9297
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Zhang, Hong-Hai, Ma, Chuanxu, Bonnesen, Peter V., Zhu, Jiahua, Sumpter, Bobby G., Carrillo, Jan-Michael Y., Yin, Panchao, Wang, Yangyang, Li, An-Ping, and Hong, Kunlun. Helical Poly(5-alkyl-2,3-thiophene)s: Controlled Synthesis and Structure Characterization. United States: N. p., 2016. Web. doi:10.1021/acs.macromol.6b01233.
Zhang, Hong-Hai, Ma, Chuanxu, Bonnesen, Peter V., Zhu, Jiahua, Sumpter, Bobby G., Carrillo, Jan-Michael Y., Yin, Panchao, Wang, Yangyang, Li, An-Ping, & Hong, Kunlun. Helical Poly(5-alkyl-2,3-thiophene)s: Controlled Synthesis and Structure Characterization. United States. doi:10.1021/acs.macromol.6b01233.
Zhang, Hong-Hai, Ma, Chuanxu, Bonnesen, Peter V., Zhu, Jiahua, Sumpter, Bobby G., Carrillo, Jan-Michael Y., Yin, Panchao, Wang, Yangyang, Li, An-Ping, and Hong, Kunlun. 2016. "Helical Poly(5-alkyl-2,3-thiophene)s: Controlled Synthesis and Structure Characterization". United States. doi:10.1021/acs.macromol.6b01233. https://www.osti.gov/servlets/purl/1265664.
@article{osti_1265664,
title = {Helical Poly(5-alkyl-2,3-thiophene)s: Controlled Synthesis and Structure Characterization},
author = {Zhang, Hong-Hai and Ma, Chuanxu and Bonnesen, Peter V. and Zhu, Jiahua and Sumpter, Bobby G. and Carrillo, Jan-Michael Y. and Yin, Panchao and Wang, Yangyang and Li, An-Ping and Hong, Kunlun},
abstractNote = {Whereas Poly(3-alkyl-2,5-thiophene)s (P3AT), with many potential applications, have been extensively investigated, their ortho-connected isomers, poly(5-alkyl-2,3-thiophene)s (P5AT), have never been reported because of the difficulty in their syntheses. We herein present the first synthesis of regioregular P5AT via controlled Suzuki cross-coupling polymerization with PEPPSI-IPr as catalyst, affording the polymers with tunable molecular weight, narrow polydispersity (PDI) and well-defined functional end groups at the gram scale. The helical geometry of P5AT was studied by a combination of NMR, small angle x-ray scattering (SAXS) and scanning tunneling microscopy (STM). Particularly, the single polymer chain of poly(5- 2 butyl-2,3-thiophene) (P5BT) on highly oriented pyrolytic graphite (HOPG) substrates with either M or P helical conformation was directly observed by STM. The comparison of UV-vis absorption between poly(5-hexyl-2,3-thiophene) (P5HT) (λ = 345 nm) and poly(3-hexyl-2,5- thiophene) (P3HT) (λ = 450 nm) indicated that the degree of conjugation of the backbone in P5HT is less than in P3HT, which may be a consequence of the helical geometry of the former compared to the more planar geometry of the latter. Moreover, we found that P5HT can emit green fluorescence under UV (λ = 360 nm) irradiation},
doi = {10.1021/acs.macromol.6b01233},
journal = {Macromolecules},
number = 13,
volume = 49,
place = {United States},
year = 2016,
month = 7
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 1work
Citation information provided by
Web of Science

Save / Share:
  • Nanoscale bulk heterojunction (BHJ) systems, consisting of fullerenes dispersed in conjugated polymers as the active component, have been actively studied over the last decades in order to produce high performance organic photovoltaics (OPVs). A significant role in device efficiency is played by the active layer morphology, but despite considerable study, a full understanding of the exact role that morphology plays and therefore a definitive method to produce and control an ideal morphology is lacking. In order to understand the BHJ phase behavior and associated morphology in these devices, we have used neutron reflection, together with grazing incidence X-ray and neutronmore » scattering and X-ray photoelectron spectroscopy (XPS) to determine the morphology of the BHJ active layer in functional devices. We have studied nine model BHJ systems based on mixtures of three poly(3-alkyl thiophenes, P3AT) (A=butyl, hexyl, octyl) blended with three different fullerene derivatives, which provides variations in crystallinity and miscibility within the BHJ composite. In studying properties of functional devices, we show a direct correlation between the observed morphology within the BHJ layer and the device performance metrics, i.e., the short-circuit current (J SC), fill factor (FF), open-circuit voltage (VOC) and overall power conversion efficiency (PCE). Using these model systems, the effect of typical thermal annealing processes on the BHJ morphology through the film thickness as a function of the polythiophene-fullerene mixtures and different electron transport layer interfaces has been determined. It is shown that fullerene enrichment occurs at both the electrode interfaces after annealing. The degree of fullerene enrichment is found to strongly correlate with J SC and to a lesser degree with FF. Finally, based on these findings we demonstrate that by deliberately adding a fullerene layer at the electron transport layer interface, J SC can be increased by up to 20%, resulting in an overall increase in PCE of 5%.« less
  • The small signal ac response is measured across the source-drain terminals of organic field-effect transistors (OFET) under dc bias to obtain the equivalent circuit parameters of poly (2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene)(PBTTT) and poly(3-hexyl thiophene)(P3HT) based devices. The numerically simulated response based on these parameters is in good agreement with the experimental data for PBTTT-FET except at low frequencies, while the P3HT-FET data show significant deviations. This indicates that the interface with the metal electrode is rather complex for the latter, involving additional circuit elements arising from contact impedance or charge injection processes. Such an investigation can help in identifying the operational bottlenecks andmore » to improve the performance of OFETs.« less