High-Performance Quantum Dot Near-Infrared Upconversion Devices Based on the Hole-Only Injection Mechanidsm

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• Colloidal quantum dot (CQD) near-infrared (NIR) upconversion devices (UCDs) convert NIR to visible light for sensing and imaging.
• Current UCDs suffer from high turn-on voltage, low efficiency, and poor current on/off ratios due to device limitations.

Purpose of the Study:

• To develop a novel CQD NIR UCD with improved performance metrics.
• To address the limitations of existing CQD upconversion technologies.

Main Methods:

• Engineered a hole-only injection mechanism to suppress electron injection.
• Utilized a liquid-phase ligand-exchange process for PbS CQD photosensitive layer (PSL) treatment.
• Optimized charge carrier balance and transport within the UCD.

Main Results:

• Achieved a record current on/off ratio exceeding 3.5 × 10^5.
• Demonstrated a high photon-to-photon (p-p) upconversion efficiency of 12.8%.
• Reduced the turn-on voltage (V_on) to 1.8 V.

Conclusions:

• The developed hole-only injection CQD NIR UCD significantly outperforms existing devices.
• This advancement offers a promising solution for efficient NIR sensing and imaging applications.
• The optimized device structure and materials pave the way for future optoelectronic innovations.