Why Sb₂Se₃/CdS Interface Produces Higher Power Conversion Efficiency

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Antimony selenide (Sb₂Se₃) solar cells are promising, but Cd-free electron transport layers (ETLs) lag behind CdS-based devices in power conversion efficiency (PCE).
• Understanding electron transfer dynamics at heterojunctions is crucial for advancing Cd-free Sb₂Se₃ solar cells.

Purpose of the Study:

• To systematically investigate Sb₂Se₃/CdS and Sb₂Se₃/ZnO heterojunctions.
• To analyze power conversion efficiency (PCE), trap state passivation, interface charge separation, and carrier kinetics.
• To identify key challenges for improving Cd-free Sb₂Se₃ solar cell performance.

Main Methods:

• Picosecond time-scale analysis of carrier kinetics.
• Comparative study of Sb₂Se₃/CdS and Sb₂Se₃/ZnO heterojunctions.
• Evaluation of PCE, passivation effects, and charge separation efficiency.

Main Results:

• Electron transfer occurs on a comparable picosecond time scale for both Sb₂Se₃/CdS (1.38–3.42 ps) and Sb₂Se₃/ZnO (1.91–3.17 ps) heterojunctions.
• The performance gap between Cd-based and Cd-free devices is primarily attributed to differences in passivation effects.
• CdS exhibits superior passivation of Sb₂Se₃, leading to higher electron transfer efficiency at the Sb₂Se₃/CdS interface.

Conclusions:

• Passivation is the critical factor limiting PCE in Cd-free Sb₂Se₃ solar cells.
• Improving passivation strategies for Cd-free ETLs is essential for high-performance devices.
• This research highlights key challenges and directions for developing efficient Cd-free Sb₂Se₃ solar cells.