Gas sensing characteristics of Au nanoparticles (AuNPs)/3-hexylthiophene-2, 5-diyl (P3HT) composite based on photocurrent detection under different irradiation wavelengths were investigated. AuNPs with different structures were prepared either by the vacuum sputtering/annealing method or by the wet chemical synthesis based on seed growth. AuNPs/P3HT composites were prepared by the dip coating method. The optical features of P3HT and Au nanostructure/P3HT composite were investigated. The optical absorption increase of AuNPs film was observed after P3HT coating, which was attributed to the interaction between the P3HT and the Au nano-islands. New shoulder peaks and the phenomenon of one spectral peak splitting into two were observed in the absorption spectra of the composite film, which confirmed the interaction between the AuNPs and the P3HT further. The photoconductivity characteristics of the P3HT and AuNPs with spectral peak position at 580-nm (AuNPs580)/P3HT composite films were investigated utilizing LED light source with different dominate wavelengths. The wavelength-dependent photocurrent change ratio I/I0 of both the P3HT and the AuNPs580/P3HT composite films was observed. The maximum I/I0 of the P3HT and AuNPs580 composite films emerged under LED irradiation with a dominate wavelength 590 nm, which was mainly ascribed to the antenna effect from the Au nano-islands, the carrier injection from nanostucture to P3HT, localized surface plasmon resonance coupling among Au nanostructures, and plasmon coupling between the Au nano-islands and the P3HT molecules. The response of Au nano-island/P3HT composite to ethanol vapor showed that the response and recovery time was shorter than 2 s. Furthermore, gas sensing characteristics were verified to be irradiation wavelength dependent. Irradiation light source with a dominate wavelength 590 nm produced the largest I/I0 1.07.
All Science Journal Classification (ASJC) codes
- Electrical and Electronic Engineering