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Keywords:

  • Oligothiophenes;
  • Polymers;
  • Semiconductors

Abstract

A series of fourfold oligothienyl-functionalized perylene bisimides, N,N′-bis(2,6-diisopropylphenyl)-1,6,7,12-tetra(4-(7-[2,2′]bithien-5-yl)-heptanoyloxyphenoxy)perylene-3,4:9,10-tetracarboxylic acid bisimide (7a), N,N′-bis(2,6-diisopropylphenyl)-1,6,7,12-tetra(4-(7-[2,2′;5′,2′′]terthien-5-yl)-heptanoyloxyphenoxy)perylene-3,4:9,10-tetracarboxylic acid bisimide (7b), and N,N′-bis(2,6-diisopropylphenyl)-1,6,7,12-tetra(4-(7-(5″-Methyl-[2,2′;5′,2″]terthien-5-yl))-heptanoyloxyphenoxy)perylene-3,4:9,10-tetracarboxylic acid bisimide (7c), have been synthesized. Oligothienyl and perylene bisimide chromophores in these dyads display their characteristic optical UV/vis absorption properties. Upon excitation of the oligothiophene subunits, fluorescence resonance energy transfer (FRET) occurs to the perylene bisimide core. Cyclic voltammetric studies revealed that the reduction of the perylene bisimide moiety is not affected by the presence of oligothiophenes, showing two waves at around -0.7 and -1.0 V versus Ag/AgCl, respectively. On the other hand, the oxidation of the oligothienyl moieties leads to oxidative coupling for 7a and 7b, providing electroactive sexithiophene- and quaterthiophene-perylene bisimide networks, respectively. Electrochemical deposition of compounds 7a,b was performed and the films were characterized using cyclic voltammetry and in situ conductance, which reveal remarkable p-type conductivity. Significantly, two separate regimes of electrical conductance have been observed for the films generated from 7b.