Ultrahigh-performance photodetectors based on low-dimensional Cs₂AgBiBr₆/CdS heterojunction.

Area of Science:

• Materials Science
• Optoelectronics
• Semiconductor Physics

Background:

• Lead-free double perovskites, specifically Cs2AgBiBr6, are promising for photoelectric devices due to stability and properties.
• Poor carrier transport in Cs2AgBiBr6 thin films limits their use in photodetection.

Purpose of the Study:

• To develop a high-performance photodetector by addressing carrier transport limitations in Cs2AgBiBr6.
• To investigate the performance enhancement of a novel Cs2AgBiBr6/CdS heterojunction.

Main Methods:

• Fabrication of a low-dimensional Cs2AgBiBr6/CdS heterojunction photodetector.
• Characterization of device performance including responsivity, specific detectivity, external quantum efficiency, and on/off current ratio.
• Utilizing scanning photocurrent mapping and band arrangement analysis to understand device mechanisms.

Main Results:

• The Cs2AgBiBr6/CdS heterojunction photodetector achieved high responsivity (6.66 × 10^3 A/W) and specific detectivity (2.10 × 10^14 Jones).
• Exceptional external quantum efficiency (1.88 × 10^6 %) and on/off current ratio (6.18 × 10^7) were recorded.
• Performance metrics significantly surpass those of previously reported Cs2AgBiBr6-based photodetectors.

Conclusions:

• The Cs2AgBiBr6/CdS heterojunction demonstrates superior performance for photodetection.
• This study presents an effective strategy for enhancing Cs2AgBiBr6-based photodetectors through heterojunction engineering.