An amphiphilic mixed (phthalocyaninato) (porphyrinato) europium(III) triple-decker complex [Pc-(OPh)(8)]Eu[Pc(OPh)(8)]Eu[TP(C CCOOH)PP] (1) with potential ambipolar semiconducting HOMO and LUMO energy levels has been designed, synthesized, and characterized. The OFET devices fabricated by quasi-Langmuir-Shafer (QLS) technique at the air/water interface with nanoparticle morphology display hole mobility of 7.0 X 10(-7) cm(2) V-1 s(-1) and electron mobility of 7.5 x 10(-7) cm(2) V-1 s(-1), which reflects its ambipolar semiconducting nature. However, the performance of the devices fabricated via a "phase-transfer" method from n-hexane with one-dimensional nanoribbon morphology was significantly improved by 3-6 orders of magnitude in terms of hole and electron mobilities, 0.11 and 4 X 10(-4) cm(2) s(-1), due to the enhanced pi-pi interaction in the direction perpendicular to the tetrapyrrole rings associated with the formation of a dimeric supramolecular structure building block depending on the intermolecular hydrogen bonding between the neighboring triple-decker molecules in the one-dimensional nanoribbons.