Flexible, ambipolar organic field-effect transistors based on the solution-processed films of octanaphthoxy-substituted bis(phthalocyaninato) europium

A new sandwich-type bis(phthalocyaninato) europium complex [Pc(OAr) 8 ]Eu[Pc(OAr) 8 ] [Pc(OAr) 8  = 2,3,9,10,16,17,23,24-octanaphthoxy phthalocyanine], was synthesized and fabricated into organic field-effect transistors devices on a flexible plastic substrate by using a simple solution-based quasi–Langmuir–Shäfer method. Ambipolar transport has been obtained in [Pc(OAr) 8 ]Eu[Pc(OAr) 8 ]-based thin film transistors with the carrier mobilities to 0.10 cm 2  V −1  s −1 for holes and 0.01 cm 2  V −1  s −1 for electrons, respectively. The energy levels of the highest occupied molecular orbital (−4.63 eV) and the lowest unoccupied molecular orbital (−3.41 eV) were obtained based on electrochemical studies of this double-decker complex. These values just simultaneously meet the energy levels required for p -type and n -type natures of organic semiconductors , suggesting the ambipolar organic semiconducting nature of this double-decker complex. Organized film microstructures and J -type molecular stacking mode for the double-decker complex in the quasi–Langmuir–Shäfer film are revealed. This study constitutes the first attempt to fabricate low-cost, flexible ambipolar phthalocyanine-based organic field-effect transistors by using simple solution-processing methods.