Effect of ZnS interfacial passivation layer to CdS quantum dot-sensitized ZnO nanorods

- The effect of ZnS layer was investigated in CdS QD-sensitized ZnO NRs.
- ZnS interfacial layer effectively passivates the surface trap states of ZnO NRs.
- ZnS layer suppresses recombination of injected electrons with holes on CdS QDs.
- The efficiency of 1.53% is increased by 300% compared with CdS/ZnO photoanode.

ZnS interfacial passivation layer was coated on ZnO nanorods (NRs) fabricated by one-step hydrothermal technique via successive ionic layer adsorption and reaction (SILAR). The ZnO NRs were further sensitized by CdS quantum dots (QDs) as a photoanode of QD-sensitized solar cells (QDSSCs). The effect of the ZnS interfacial passivation layer on the performance of the QDSSCs was systematically investigated by varying the SILAR cycle number. The ZnS layer with an appreciated thickness not only suppressed the recombination of injected electrons with holes on the CdS QDs but also effectively passivated the surface trap states of ZnO NRs and increased the deposition of CdS QDs. These characteristics improved the light-harvesting efficiency of the photoelectrode. The conversion efficiency of the CdS QD-sensitized ZnO NRs with ZnS interfacial passivation layer could reach a maximum of 1.53%, which was enhanced by 300% compared with that of the cell based on CdS QD-sensitized ZnO NRs (0.51%).

The illustration on energy band diagram of CdS/ZnS/ZnO NRs photoanode, and J-V characteristics of the QDSSCs with ZnO, CdS/ZnO and CdS/ZnS/ZnO photoelectrodes with different amounts of ZnS.262