High-performance solution-processed TIIG-based polymer photodetector with detectivity across scalable SWIR...

Area of Science:

• Organic electronics
• Semiconductor devices
• Materials science

Background:

• Developing cost-efficient, flexible, and RoHS-compliant SWIR photodetectors for roll-to-roll processing is challenging.
• Existing methods often involve complex, multi-step processes and vacuum deposition, limiting scalability and increasing costs.

Purpose of the Study:

• To present a simplified organic metal-semiconductor-metal (MSM) photodetector using a novel ultralow-bandgap polymer.
• To demonstrate a cost-efficient and flexible SWIR photodetector compatible with industrial-scale roll-to-roll manufacturing.

Main Methods:

• Synthesized a new thienoisoindigo-based ultralow-bandgap polymer (TIIG-Se-DFT) with selenophene and fluorinated thiophene units.
• Created a single bulk heterojunction active layer by blending TIIG-Se-DFT with the nonfullerene acceptor Y6.
• Fabricated a simplified MSM photodetector with interdigitated Au electrodes and a single solution-processed active layer.

Main Results:

• The TIIG-Se-DFT:Y6 photodetector exhibits strong absorption from 700-1600 nm with a narrow bandgap of 0.96 eV.
• Achieved a specific detectivity (D*) of ≈2 × 10^11 Jones at 1150 nm and >0.13 × 10^10 Jones at 1550 nm.
• Demonstrated fast response times (86/36 µs rise/fall), low dark current (4.6 × 10^-8 A cm^-2), and excellent ambient stability (>95% responsivity after 800 hours).

Conclusions:

• The simplified, high-sensitivity TIIG-Se-DFT:Y6 SWIR photodetector advances toward industrial-scale production.
• The solution-processed, flexible, and RoHS-compliant nature makes it suitable for wearables, LiDAR, and optical communications.
• This work offers a promising pathway for next-generation SWIR sensing technologies.