UV sensing of twinned ZnO–PANI composite

A novel twinned ZnO–polyaniline (PANI) composite was fabricated through a chemical method using zinc acetate hexahydrate and ammonium hydroxide with the addition of 15 wt%PANI. Pure ZnO and composite were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Raman spectroscopy, and UV–visible spectrophotometer. FESEM images revealed that ZnO–PANI composite has a twinned rod microstructure, with homogeneous size distribution; the average length of rods becomes shorter, while the average diameter becomes larger with the addition of PANI. XRD analysis confirms the formation of the hexagonal wurtzite ZnO structure. With the addition of PANI, the original structure of ZnO remains stable. Raman peaks were observed, which were associated with the interfacial interactions between ZnO and PANI molecular chains. The use of porous Si substrates is found to be very beneficial to favor the bonding strength between the as-grown composite and Si substrate. The optical bandgap estimated from absorbance decreases from 3.22 to 3.05 eV. The fabricated photodetector based on the newly synthesized twinned rod-like ZnO–PANI composite revealed high gain of 5.23 and better sensitivity than pure ZnO. This enhancement can be attributed to the presence of PANI, which absorbs more light in the visible region.