Band engineered ternary solid solution CdSxSe1-x-sensitized mesoscopic TiO2 solar cells.

Area of Science:

• Materials Science
• Photovoltaics
• Nanotechnology

Background:

• Efficient light harvesting and charge separation in semiconductor-sensitized solar cells (SSCs) depend on the optical band gap of light absorbers and their band alignment with metal oxides.
• Optimizing band alignment in CdSe-sensitized TiO2 often requires quantum-sized CdSe, leading to photon loss from quantum confinement effects.

Purpose of the Study:

• To develop a novel semiconductor sensitizer for TiO2 that overcomes limitations of existing materials.
• To investigate the potential of ternary cadmium sulfoselenide (CdSxSe1-x) as a light absorber in SSCs.

Main Methods:

• Synthesis of CdSxSe1-x by alternately depositing CdS and CdSe layers under ambient conditions.
• Fabrication and testing of SSCs using CdSxSe1-x-sensitized TiO2 with a polysulfide electrolyte and Cu2S counter electrode.
• Evaluation of power conversion efficiency under simulated AM1.5 illumination.

Main Results:

• Successful synthesis of CdSxSe1-x with tunable band gaps without dimensional reduction.
• SSCs utilizing CdSxSe1-x demonstrated a power conversion efficiency of 4.05%.
• Performance rivalled cascaded CdS/CdSe electrodes in polysulfide electrolytes.

Conclusions:

• CdSxSe1-x presents a viable alternative for optimizing semiconductor sensitizers in SSCs.
• This approach enhances charge separation while maintaining efficient light harvesting.
• The findings offer a new strategy for improving SSC performance.