Hydrogen gas sensor utilizing a high proton affinity of p-diketodipyridylpyrrolopyrrole

摘要

Organic pigments were once extensively investigated as photoconductors for the electrophotographic photoreceptor. Nowadays, they play an important role as colorants for color copies as well as materials for optical discs, electroluminescence, FET etc. Here, we report another novel application of organic pigments for H_2 gas sensors. A high-performance hydrogen gas sensor has been developed that utilizes a proton affinity of 1,4-diketo-3,6-bis-(4'-pyridyl)-pyrrolo-[3,4-c]-pyrrole (DPPP) known as a red pigment. We found that the N atom of the pyridyl ring of the DPPP can easily be protonated by protons dissociated from H_2 to induce a remarkable change in electrical conductivity by several orders of magnitude. The appealing feature of the device is the reversible operation at room temperature as characterized by a change in electrical resistivity by two orders of magnitude even under 0.05 % H_2.