A-D-A Molecular Design Strategy Enabling Ultrasensitive NIR Vapor Sensing

Area of Science:

• Organic semiconductor materials
• Fluorescent chemosensors
• Near-infrared (NIR) spectroscopy

Background:

• Thin-film fluorescent chemosensors offer tunable design, high selectivity, and sensitivity for gas detection.
• Achieving simultaneous sensitivity, selectivity, and stability (3S attributes) is challenging, especially for NIR gas detection.

Purpose of the Study:

• To develop a novel organic semiconductor fluorescent material for enhanced NIR gas detection.
• To address the limitations of conventional visible fluorescent materials in gas sensing applications.

Main Methods:

• Employed an acceptor-donor-acceptor (A-D-A) molecular design strategy.
• Synthesized a NIR fluorescent thin film, C8-IDTT-IC, with peak emission at 790 nm.
• Evaluated material properties including selectivity, sensitivity, response time, and optical damage resistance.

Main Results:

• The C8-IDTT-IC thin film exhibited excellent resistance to background light and optical damage.
• Achieved remarkable selectivity for biogenic amines with a detection limit of 116 ppb.
• Demonstrated a rapid response time (<30 s) and low optical damage rate (3% over 1800 s).

Conclusions:

• The developed NIR fluorescent material successfully integrates the 3S attributes for gas detection.
• The material's practical utility was shown through integration into a hand-held detector for real-time food spoilage monitoring.
• This work advances NIR fluorescent thin films for sensitive and stable gas sensing applications.