Heavy Metal Free Ag₂Se Quantum Dot Inks for Near to Short-Wave Infrared Detection

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Infrared (IR) photodetectors are crucial for applications like environmental monitoring and autonomous navigation.
• Current HgCdTe and InGaAs technologies are expensive and difficult to scale.
• Heavy-metal-free colloidal quantum dots (cQDs) are promising but often rely on toxic elements.

Purpose of the Study:

• To develop high-performance, heavy-metal-free IR photodetectors using Ag2Se cQDs.
• To demonstrate a simplified fabrication process using solution phase ligand exchange (SPLE).
• To evaluate the performance of Ag2Se cQD photodetectors for near- to short-wave IR applications.

Main Methods:

• Fabrication of Ag2Se cQD photodetectors via a single-step SPLE process.
• Characterization of photoconductor responsivity in the 800-1250 nm range.
• Demonstration of a self-powered photodiode with performance metrics including specific detectivity, bandwidth, and response time.

Main Results:

• SPLE enabled reproducible Ag2Se cQD photodetectors with a single-step deposition.
• Photoconductors achieved responsivities of ~150 mA/W at 0.3 V bias (800-1250 nm).
• Self-powered photodiodes demonstrated a specific detectivity of 6.5 × 10^10 Jones at 1200 nm, with 18 kHz bandwidth and sub-50 μs response times.

Conclusions:

• Ag2Se cQDs are a viable, heavy-metal-free alternative for IR detection.
• The SPLE method offers a scalable and regulatory-compliant fabrication strategy.
• This work paves the way for improved Ag2Se cQD performance in midwave IR detection.