Thiophene–Benzothiadiazole Co-Oligomers: Synthesis, Optoelectronic Properties, Electrical Characterization, and Thin-Film Patterning

Authors

  • Manuela Melucci,

    Corresponding author
    1. Istituto per la Sintesi Organica e la Fotoreattività (ISOF) Consiglio Nazionale Ricerche via P. Gobetti, 101, 40129 Bologna (Italy)
    • Istituto per la Sintesi Organica e la Fotoreattività (ISOF) Consiglio Nazionale Ricerche via P. Gobetti, 101, 40129 Bologna (Italy)
    Search for more papers by this author
  • Laura Favaretto,

    1. Istituto per la Sintesi Organica e la Fotoreattività (ISOF) Consiglio Nazionale Ricerche via P. Gobetti, 101, 40129 Bologna (Italy)
    Search for more papers by this author
  • Alberto Zanelli,

    1. Istituto per la Sintesi Organica e la Fotoreattività (ISOF) Consiglio Nazionale Ricerche via P. Gobetti, 101, 40129 Bologna (Italy)
    Search for more papers by this author
  • Massimiliano Cavallini,

    1. Istituto per i Materiali Nanostrutturati (ISMN) Consiglio Nazionale Ricerche via P. Gobetti 101, 40129 Bologna (Italy)
    Search for more papers by this author
  • Alessandro Bongini,

    1. Università di Bologna Dipartimento di Chimica “G. Ciamician” via F. Selmi, 2, 40122 Bologna (Italy)
    Search for more papers by this author
  • Piera Maccagnani,

    1. Istituto per la Microelettronica e i Microsistemi (IMM) Consiglio Nazionale Ricerche via P. Gobetti 101, 40129 Bologna (Italy)
    Search for more papers by this author
  • Paolo Ostoja,

    1. Istituto per la Microelettronica e i Microsistemi (IMM) Consiglio Nazionale Ricerche via P. Gobetti 101, 40129 Bologna (Italy)
    Search for more papers by this author
  • Gwennaelle Derue,

    1. Service de Chimie des Matériaux Nouveaux Université de Mons/Materia Nova 20, Place du Parc, B-7000 Mons (Belgium)
    Search for more papers by this author
  • Roberto Lazzaroni,

    1. Service de Chimie des Matériaux Nouveaux Université de Mons/Materia Nova 20, Place du Parc, B-7000 Mons (Belgium)
    Search for more papers by this author
  • Giovanna Barbarella

    1. Istituto per la Sintesi Organica e la Fotoreattività (ISOF) Consiglio Nazionale Ricerche via P. Gobetti, 101, 40129 Bologna (Italy)
    Search for more papers by this author

Abstract

Newly synthesized thiophene (T) and benzothiadiazole (B) co-oligomers of different size, alternation motifs, and alkyl substitution types are reported. Combined spectroscopic data, electrochemical analysis, and theoretical calculations show that the insertion of a single electron-deficient B unit into the aromatic backbone strongly affects the LUMO energy level. The insertion of additional B units has only a minor effect on the electronic properties. Cast films of oligomers with two alternated B rings (B–T–B inner core) display crystalline order. Bottom-contact FETs based on films cast on bare SiO2 show hole-charge mobilities of 1 × 10−3–5 × 10−3 cm2 V−1s−1 and Ion/Ioff ratios of 105–106. Solution-cast films of cyclohexyl-substituted compounds are amorphous and do not show FET behavior. However, the lack of order observed in these films can be overcome by nanorubbing and unconventional wet lithography, which allow for fine control of structural order in thin deposits.

Ancillary