Phenacyl-thiophene and quinone semiconductors designed for solution processability and air-Stability in high mobility n-channel field-effect transistors www.chemeurj.org

Joseph A. Letizia, Scott Cronin, Rocio Ponce Ortiz, Antonio Facchetti, Mark A. Ratner, Tobin J. Marks

Research output: Contribution to journalArticle

56 Citations (Scopus)

Abstract

Electron-transporting organic semiconductors (n-channel) for fieldeffect transistors (FETs) that are processable in common organic solvents or exhibit air-stable operation are rare. This investigation addresses both these challenges through rational molecular design and computational predictions of n-channel (FETs) air-stability. A series of seven phenacyl-thiophene-based materials are reported incorporating systematic variations in molecular structure and reduction potential. These compounds are as follows: 5,5‴-bis(perfluorophenylcarbonyl)-2,2′:5′,-2″:5″, 2‴-quaterthiophene (1), 5,5‴-bis-(phenacyl)-2,2′;5′, 2″: 5″,2‴-quaterthiophene (2), poly[5,5‴- (perfluorophenac-2-yl)-4′,4″-dioctyl-2,2':5',2":5", 2'"-quaterthiophene) (3), 5,5‴-bis(perfluorophenacyl)-4,4‴- dioctyl-2,2′:5′,2″:5″,2‴-quaterthiophene (4), 2,7-bis((5-perfluorophenacyl)thiophen-2-yl)-9,10phenanthrenequinone (5), 2,7-bis[(5phenacyl)thiophen-2-yl]-9,10-phenanthrenequinone (6), and 2,7-bis(thiophen-2-yl)-9,10-phenanthrenequinone, (7). Optical and electrochemical data reveal that phenacyl functionalization significantly depresses the LUMO energies, and introduction of the quinone fragment results in even greater LUMO stabilization. FET measurements reveal that the films of materials 1, 3, 5, and 6 exhibit n-channel activity. Notably, oligomer 1 exhibits one of the highest, μe (up to ≈0.3 Cm 2V-1S-1) values reported to date for a solutioncast organic semiconductor; one of the first n-channel polymers, 3, exhibits μe ≈ 10-6 Cm2V -1S-1 in spin-cast films (μc = 0.02 cm 2 V-1S-1 for drop-cast 1:3 blend films); and rare air-stable n-channel material 5 exhibits n-channel FET operation with μe = 0.015 cm2V-1s-1, while maintaining a large Ion:off= 106 for a period greater than one year in air. The crystal structures of 1 and 2 reveal close herringbone interplanar π-stacking distances (3.50 and 3.43 Å, respectively), whereas the structure of the model quinone compound, 7, exhibits 3.48 Å cofacial π-stacking in a slipped, donor-acceptor motif.

Original languageEnglish
Pages (from-to)1911-1928
Number of pages18
JournalChemistry - A European Journal
Volume16
Issue number6
DOIs
Publication statusPublished - Feb 8 2010

Keywords

  • Phenacyl-thiophene
  • Polymers
  • Quinones
  • Semiconductors

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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