Air-stable and ultrasensitive solution-cast SWIR photodetectors utilizing modified core/shell colloidal quantum dots

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Indium Gallium Arsenide (InGaAs) photodetectors are standard for short-wave infrared (SWIR) detection but are costly.
• Lead Sulfide (PbS) quantum dots (QDs) offer a cost-effective alternative with tunable properties but suffer from poor stability and carrier transfer.
• Existing PbS QD photodetectors face limitations in performance and long-term reliability.

Purpose of the Study:

• To develop a cost-efficient and stable SWIR photodetector.
• To enhance carrier transfer efficiency and photo/thermal stability in PbS QD photodetectors.
• To overcome the limitations of current PbS QD-based SWIR detection technologies.

Main Methods:

• Incorporation of Cadmium Sulfide (CdS) into PbS QD shells.
• Fabrication of SWIR photodetectors using thick-shell PbS/CdS QDs.
• Surface passivation of QDs to improve stability.

Main Results:

• Achieved a high on/off ratio of 11.25.
• Reached a high detectivity of 4.0 × 10^12 Jones, a >10x improvement over bare PbS QDs.
• Significantly enhanced long-term stability and device lifetime due to CdS shell and self-passivation.

Conclusions:

• The proposed PbS/CdS core-shell QD structure effectively enhances SWIR photodetector performance.
• CdS shell incorporation provides efficient carrier transfer and robust stability against oxidation.
• This method presents a promising pathway for low-cost, high-performance SWIR photodetectors.