Broadband enhancement in absorption cross-section of N719 dye using different anisotropic shaped single crystalline silver nanoparticles

Abstract

We have synthesized spherical as well as different anisotropic shapes of Ag nanoparticles using chemical reduction of silver nitrate with different sodium borohydride and cetyltrimethylammonium bromide (CTAB) concentrations. The X-ray diffraction of all synthesized Ag nanoparticles revealed a fcc structure. Further capping of CTAB on the surface of Ag nanoparticles was confirmed by Fourier transform infrared spectroscopy. Morphological analysis using transmission electron microscopy showed the formation of different anisotropic shapes such as oval, rod, cubic, pentagonal and prismatic when the CTAB concentration was maintained at 4 mM. The single crystalline nature of all different shaped Ag nanoparticles was confirmed by Nano beam diffraction patterns. The presence of multiple Surface Plasmon Resonance (SPR) peaks for different anisotropic shapes of Ag nanoparticles was revealed by UV-vis spectroscopy and was further utilized in commonly used N719 dye in dye sensitized solar cells. It was observed that the incorporation of different anisotropic Ag nanoparticle shapes into the dye resulted in a broadband enhancement of its absorption (∼65%), which is much greater as compared to that incorporating spherical Ag nanoparticle shape (∼21%). This enhancement was attributed to the improvement in the effective cross-section of the dye upon incorporation of different anisotropic Ag nanoparticle shapes.