Photoelectrical properties in poly(alkyl/alkoxy-terthiophenes): Dependence on the alkyl-chain length

Abstract

The length of the alkyl-groups affects both the spectrophotometric and the electrochemical properties of poly(alkoxy-alkyl-terthiophenes) films prepared by cyclic voltammetry. The maximum absorbance shifts towards higher wavelengths and the oxidation peak towards cathodic potentials as the alkyl-chain length increases. Moreover, it was found that the photoelectrical performance exhibited by poly(alkoxy-alkyl-terthiophenes)-based devices improved from poly(4,4″-dipenthoxy-3′-dodecyl-2,2′:5′ ,2″-terthiophene) to poly(4,4″-dipenthoxy-3′-hexyl-2,2′:5′, 2″-terthiophene), probably due to an increasing hopping mobility, and remained constant or somewhat decreased by going from poly(4,4″-dipenthoxy-3′-hexyl-2,2′:5′, 2″-terthiophene) to poly(4,4″-dimethoxy-3′-methyl-2,2′:5′,2″ -terthiophene) possibly for a lower planarity of polythiophene chains. © 2001 Elsevier Science B.V. All rights reserved.