Ambipolar chemical sensors based on the self-assembled film of an amphiphilic (phthalocyaninato) (porphyrinato) europium complex

Abstract An amphiphilic mixed (phthalocyaninato) (porphyrinato) europium triple-decker complex Eu 2 (Pc) 2 (TPyP) has been synthesized and characterized. Introducing electron-withdrawing pyridyl substituents onto the meso-position of porphyrin ring in the triple-decker to ensure the sufficient hydrophilicity and suitable HOMO and LUMO energy levels and thus successfully realize amphiphilic ambipolar organic semiconductor. Importantly, high sensitive, reproducible p -type and n -type responses towards NH 3 and NO 2 respectively, based on the self-assembled film of the Eu 2 (Pc) 2 (TPyP) fabricated by a simple solution-based Quasi–Langmuir–Shafer (QLS) method, have been first revealed. The good conductivity and crystallinity for the QLS film of Eu 2 (Pc) 2 (TPyP) render it excellent sensing property for both electron-donating gas NH 3 in 5–30 ppm range and electron-accepting gas NO 2 in 400–900 ppb range due to the optimized molecular packing in the uniform-sized nanoparticles depending on the effective intermolecular interaction between the triple-decker molecules, among the best results of phthalocyanine-based chemical sensors for room-temperature detection of NH 3 and NO 2 , respectively. Furthermore, the responses of the QLS film are all linearly correlated to both NH 3 and NO 2 with excellent sensitivity of 0.04% ppm − 1 and 31.9% ppm − 1 , respectively, indicating the great potential of semiconducting tetrapyrrole rare earth triple-decker compounds in the field of chemical sensors.