Iridium-palladium binary alloy as a counter electrode in dye-sensitized solar cells.

This study is concerned with the iridium-palladium (Ir-Pd) binary alloy as a counter electrode (CE) for DSSC. The CE was prepared using the liquid phase deposition (LPD) technique. The influence of the concentration of hydrogen hexachloroiridate(IV) hydrate (H 2 Cl 6 Ir·H 2 O) on the properties and the performance of the device was investigated. The source of iridium was H 2 Cl 6 Ir·H 2 O. XRD analysis confirmed that the dominant phase of Ir-Pd existed in the sample. The grain size of Ir-Pd increased with the increase in the concentration of H 2 Cl 6 Ir·H 2 O until an optimum concentration of 0.7 mM was reached. The % wt of Ir was found to increase with the concentration of H 2 Cl 6 Ir·H 2 O. The device utilizing Ir-Pd CE with 0.7 mM H 2 Cl 6 Ir·H 2 O demonstrated the highest power conversion efficiency (PCE) of 5.84%, beating that of the device with Pt CE having a PCE of 5.04%. This is because the device possesses the lowest charge transfer resistance ( R ct ), highest recombination resistance ( R cr ), and longest carrier lifetime ( τ ), and the device possesses the highest reduction current ( J pc ) and incident-photon conversion efficiency (IPCE). The PCE was significantly affected by Ir content in the binary alloy of Ir-Pd. According to the PCE result, Ir-Pd CE was found as a suitable substitution for Pt as CE for the device.