Silver–copper nanoalloys-an efficient sensitizer for metal-cluster-sensitized solar cells delivering stable current and high open circuit voltage

Abstract

Metal clusters (CLs) are recognized as a new class of sensitizers in a metal-cluster-sensitized solar cell (MCSC) which is an extension to well-recognized dye-sensitized solar cells (DSSCs). The function performed by dyes in DSSCs has predominately been executed by metal CLs in MCSCs. The distinct behavior of CLs at nano-scaled level can enhance their significance in photovoltaic applications. Recently, metal CLs have been explored as sensitizers in a solar cell, and the efficiency of the cell has been reported to be more than 2%. Herein, we present glutathione-protected Ag–Cu bimetallic CLs (alloyed CLs or nanoalloys) as sensitizer in MCSCs. Spray-coating technique has been employed to deposit CLs on photoanodes. The TiO2 modified with Cu rich alloyed CLs exhibit the short circuit photocurrent (Jsc) of 2.87 mAcm−2 with Voc of 691 mV. EIS and Mott–Schottky analysis have been performed to explicate the processes occurring inside MCSCs. Comparative study has been conducted to elucidate the effect of alloying on photo-electrochemical (PEC) response. Our results lay the foundations for exploring other nanoalloys as sensitizers in solar cells because nanoalloys present a greater degree of flexibility in properties, structure, size, and the composition of the constituent elements.