Efficiency enhancement in SnO2 based dye-sensitized solar cells by incorporating plasmonic gold nanoparticles

SnO₂ is an attractive semiconducting material which can be used in place of TiO₂ in dye–sensitized solar cells (DSSCs) due to the wide energy band gap, good photostability and high charge carrier mobility. Here we report the use of plasmon resonance effect by gold nanoparticles of size 70–80 nm for efficiency enhancement in solar cells made with SnO₂ photoanodes and sensitized with Indoline D149 dye. Devices were characterized by current density–voltage (J–V) curves, incident photon–to–electron conversion efficiency (IPCE) spectroscopy and electron impedance spectroscopy (EIS). DSSCs fabricated with pristine SnO₂ photoanode showed efficiency of (η) 2.28%, under the illumination of 100 mW cm^-2 (AM 1.5), whereas DSSCs fabricated with optimized Au nanoparticles in the SnO₂ photoanode showed efficiency of 2.89% having more than 26% enhancement. This increase is mainly attributed to the 42% increase in the short circuit current density from 6.48 mA cm^-2 to 9.19 mA cm^-2 caused by the plasmonic effect by Au nanoparticles. The IPCE was also increased due to the use of Au@SnO₂. According to the EIS analysis, the incorporation of plasmonic Au nanoparticles has led to a 35% decrease in the interfacial charge transfer resistance (R_CT2) at the SnO₂ photoanode/electrolyte interface which is associated with the increased rate of charge transfer at this interface and increased resulting the efficiency of the solar cells.