Efficacy of In₂S₃ interfacial recombination barrier layer in PbS quantum-dot-sensitized solar cells

In₂S₃ interfacial recombination barrier layer (IBL) via successive ionic layer adsorption and reaction (SILAR) was successfully employed between PbS quantum dots and mesoporous TiO₂ in quantum-dot-sensitized solar cells (QDSSCs). In₂S₃ IBL significantly increased the resistance against back electron transfer from TiO₂, resulting an increment in the photocurrent density (J_SC) for the cell with single SILAR cycle of In₂S₃ IBL. Further increase in the number of SILAR cycles of In₂S₃ IBL deteriorated the J_SC, whereas open-circuit voltage sustained the increasing trend. Therefore, an optimal photo-conversion efficiency of ∼2.2% was obtained for the cell with 2 SILAR cycles of In₂S₃ IBL, which strategically reached a value of ∼2.70% after annealing (increased by 40% compared to the control cell without IBL). In₂S₃ IBL not only improved the recombination resistance and electron life time of the cells, but it also enhanced the photostability of the cells. - Highlights: • In₂S₃ interfacial recombination barrier layer was deposited on TiO₂ photoanode via SILAR process. • Resistance against back electron transfer from TiO₂ (recombination) increased notably. • Fabricated PbS-QDSSCs were characterized using IPCE, OCVD and EIS techniques. • In₂S₃ IBL improved chemical capacitance, electron life time and photostability of modified cells. • 2In₂S₃ IBL showed optimal performance, yielding 40% improvement in PCE after heat treatment.