Modification of light absorption in thin CuInS^sub 2^ films by sprayed Au nanoparticles

The chemical spray pyrolysis method was used to deposit CuInS^sub 2^ (CIS) thin films and Au nanoparticles (NPs) in two configurations: glass/Au-NP layer covered with CuInS^sub 2^ film (Au-NP/CIS) and glass/CuInS^sub 2^ films covered with Au-NP layer (CIS/Au-NP). According to X-ray diffraction (XRD), the spray of 2 mM HAuCl^sub 4^ aqueous solution with a volume of 2.5 to 15 ml onto a glass substrate at 340°C results in metallic Au nanoparticles with a similar mean crystallite size in the range of 30-38 nm. The mean crystallite sizes remain in the range of 15-20 nm when grown onto a CIS film. The prepared films show plasmonic light absorption with increasing intensity in the spectral range of 500- 800 nm when increasing the volume of HAuCl^sub 4^ solution sprayed. When compared to bare CIS on glass, the absorptance was increased ca. 4.5 times in the case of glass/Au-NP/CIS and ca. 3 times in the case of glass/CIS/Au-NP configuration. The glass/Au-NP/CIS configuration had an advantage since Au-NP could be embedded without chemically damaging the CIS.