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

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 as 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 photo-anodes. The TiO2 modified with Cu rich alloyed CLs exhibit the short circuit photocurrent (Jsc) of 2.87 mAcm(-2) with V-oc of 691 my. 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. (C) 2015 Elsevier B.V. All rights reserved.