Study of NO₂ sensing properties of UV activated graft comb copolymer and ZnO blends in ppm and sub-ppm range at room temperatures

In this work, novel organic-inorganic blend, made from PEGSil (Poly(dimetylsiloksan)-co-[poli(metylohydrosiloksane)-graft-2-winyl-poly(3-heksylthiophene)]-co-[poly(dimetylsiloksane)-graft- metakrylane ethere metylene poly(etylene glicole)]]) mixed with zinc oxide nanomaterial was studied as the sensitive layer for the nitrogen dioxide (NO₂) resistance gas sensor application. Moreover, the PEGSil graft copolymer material was tested in two variants, defined by side-chain length of P3HT: shorter hexane fraction (H) and longer chloroform fraction (CH). Elaborated organic-inorganic blend was deposited on interdigital transducers (Au on Si/SiO2) by drop coating method from chlorobenzene based mixture. Sensor response characteristics to different concentrations of NO₂ (1-10 ppm) in N₂ carrier gas and synthetic air were measured and compared. Measurements were done at room temperature with UV light charge carriers activation. What is more, measurements for low gas concentrations (50-500 ppb) were done and analyzed. Obtained results shows that the sensitivity of fabricated sensors is about 6.8% per 1 ppb for hexane fractions of PEGSil and 9.3% for chloroform fractions in the concentration range from 50 to 200 ppb of NO₂ in N₂ carrier gas. This results show that blend of these materials have a huge potential as a sensing layer for NO_x low concentration sensing.