Pt- and TCO-Free Flexible Counter Electrodes for Dye-Sensitized Solar Cells

Dye-sensitized solar cells (DSSCs) have attracted extensiveattention as low cost, easy manufacturingprocess and acceptedphotovoltaic performance. Typically, a DSSC includes a dye-sensitizedsemiconductor photoanode, an I⁻/I₃⁻ redox electrolyte and a Pt counter electrode (CE). As a crucial component in DSSCs, the basicfunctions of a CE are to increase the transfer of the electrons from the external circuit back to the electrolyte and accelerate the reduction reaction from I₃⁻to I⁻.Nevertheless, limited resources and high prices would restrict the application of Pt thin film coated on a transparent conducting oxide (TCO).To solve this issue, several alternatives have been proposed to serve as TCO-freeand Pt-free CEs for DSSCs.

In this study, Ni₃S₂/Ni−P hybrid film coated on a flexible polyimide (PI) substrate was employed as a TCO-free and Pt-free flexible CE for DSSCs. The bilayer Ni₃S₂/Ni−P hybrid film was deposited on a polyimide (PI) plastic substrate by using a series of chemical/electrochemical treatments/processes. As a result, the DSSC assembled with the Ni₃S₂/Ni−P coated PI flexible CE displayed an impressive photovoltaic conversion efficiency of 6.28%.