文摘
Solution processed Langmuir-Schäfer and cast thin films of regioregular poly(2,5-dioctyloxy-1,4-phenylene-alt-2,5-thienylene) are investigated as transistor active layers. The study of their field-effectproperties evidences that no transistor behavior can be seen with a cast film channel material. This wasnot surprising considering the twisted conformation of the polymer backbone predicted by varioustheoretical studies. Strikingly, the Langmuir-Schäfer (LS) thin films exhibit a field-effect mobility of 5× 10-4 cm2/V·s, the highest attained so far with an alkoxy-substituted conjugated polymer. Extensiveoptical, morphological, and structural thin-film characterization supports the attribution of the effect tothe longer conjugation length achieved in the Langmuir-Schäfer deposited film, likely due to an improvedbackbone planarity. This study shows that a technologically appealing deposition procedure, such as theLS one, can be exploited to significantly improve the inherently poor field-effect properties of twistedconjugated backbones. This achievement could promote the exploitation for electronic, and possiblysensing, applications of the wealth of opportunities offered by the alkoxy substitution on the phenyleneunits for convenient tailoring of the phenylene-thienylene backbone with molecules of chemical andbiological interest.
