Synergistic effects of Pt-Ni alloy-decorated carbon black nanofillers on performance and stability of quasi-solid-state dye-sensitized solar cells

Abstract

Quasi-solid-state dye-sensitized solar cells (QSDSCs) feature better stability and facile packaging in contrast with typical dye-sensitized solar cells (DSCs) using volatile liquid electrolytes. However, the performance and stability of QSDSCs are strongly influenced by nanofillers, whose role in the composite polymer electrolyte remains insufficiently understood. In this regard, a series of Pt-Ni alloys on carbon blacks (CBs) were synthesized using a microwave-assisted method, enabling a systematic investigation of these materials as nanofillers in QSDSCs for the first time. The nanofillers of CBs decorated with highly catalytic Pt can function as the extended counter electrode, which can improve the short-circuit current density by reducing charge transfer resistance at the counter electrode/electrolyte interface and improving the electrolyte conductivity. Additionally, alloying Pt with Ni on CBs can increase recombination resistance at the interface between the dye-adsorbed TiO₂ photoanode and electrolyte. This minimizes voltage losses by reducing the concentration of free I₃^- ions in the electrolyte, leading to an improvement in the open-circuit voltage. The Ni content in Pt-Ni alloys can further prevent Pt dissolution in the redox electrolyte through a competitive dissolution, enhancing long-term stability in iodine-based electrolytes. As a result, QSDSCs using optimized Pt-Ni/CB nanofillers simultaneously achieve the comparable conversion efficiency and improved stability. This synergistic enhancement suggests that the optimal nanofiller properties in QSDSCs can be achieved through controlling the decoration of varied alloys on CBs to meet critical performance and stability requirements.