Biosynthesis of large area (30×30 cm2) silver thin films

For the first time, biosynthesis of large area (30×30 cm2) silver thin films onto glass substrates using chemical successive ionic layer adsorption and reaction (SILAR) method is reported. The SILAR deposition method is relatively inexpensive and convenient for large area deposition of metal thin films. Silver nanostructurals are deposited using AgNO3 solution and guava leaves extract. The characteristics of silver thin films are studied using UV–visible spectrophotometer, scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM), contact angle and photoluminescence (PL) techniques. The UV–visible spectrophotometer confirmed the formation of silver thin film. Also, the absorbance spectra confirmed that the silver thin films exhibit absorption maximum at 435 nm, which is a characteristic feature of surface plasmon resonance (SPR) peak for silver nanoparticles. The scanning electron microscopy (SEM) images showed the formation of aggregated silver nanoparticle with increasing thicknesses. The AFM study showed that the silver nanoparticles are nonuniform on the substrate surface. The XRD analyses confirmed the nanocrystalline phase of silver thin film with face center cubic (FCC) crystal structure. Contact angle measurement suggested that the film is hydrophilic in nature. The silver thin films are found to be photoluminescent with a characteristic peak at 479 nm. The present study demonstrates an easy method for biosynthesis of large area silver thin films using green and ecofriendly SILAR method. Finally, as an application these films are used effectively in antibacterial activity study.