Alloy counter electrodes in dye-sensitized solar cells

Abstract

Dye-sensitized solar cells (DSSCs) have gained widespread attention of researchers in recent years due to their unique advantages, such as low cost of production, ease of manufacturing and relatively high power conversion efficiency. Traditionally, a DSSC has several components including photoanode material, dyes, electrolytes and the counter electrode (CE), which must cooperate intimately to transform incident light into current. As a crucial part of DSSCs, designing CE with excellent properties is a key to improve the power conversion efficiency of DSSCs. As the good CE material, noble metal Pt material exhibiting high catalytic activity and electrical conductivity has obtained high power conversion efficiency in DSSCs. However, some problems of Pt, especially high scarcity in the nature and the corrosivity of I–/I3– electrolyte, limit its further application in DSSCs. Meanwhile, lots of Pt-free materials involving carbon materials, transition metal compounds, polymers, and hybrids have been developed as CE materials to solve the challenges of the Pt-based DSSCs, and achieved favorable power conversion efficiency. Recently, another novel type of alloy materials, which include Pt-based and Pt-free alloys, show superior catalytic activity and have achieved significant power conversion efficiency when applied as CEs in DSSCs. The alloy materials have the merits of simple preparation process and low cost and are the outstanding candidate to replace Pt in DSSCs. The present review gives a summary of the alloy materials as CE in DSSCs. We stress the advantages and disadvantages of alloy CE materials, and put forward ideas for preparation methods, DSSCs’ designing, ab-initio Car-Parrinello molecular dynamics simulations, first-principle density functional theory calculations and stability evaluations in future research for DSSCs featuring alloy CEs. Also, some crucial issues in alloy-based DSSCs and the further applications of the alloy materials in other field of catalysis are discussed.