Quantum-Size-Effect Tuning Enables Narrowband IR Photodetection with Low Sunlight Interference

Area of Science:

• Optoelectronics
• Materials Science
• Quantum Dot Technology

Background:

• Infrared photodetection is crucial for depth imaging technologies like structured light and time-of-flight.
• Silicon (Si) photodetectors are limited to wavelengths below 1100 nm due to their bandgap.
• Operation at 1370 nm offers reduced sunlight interference due to atmospheric absorption.

Purpose of the Study:

• To report 1370 nm-operating colloidal quantum dot (CQD) photodetectors.
• To evaluate the outdoor performance of these CQD photodetectors.
• To enhance signal-to-background ratio for infrared depth imaging.

Main Methods:

• Developed a surface-ligand engineering strategy to tune CQD electronic properties.
• Fabricated photodetectors using an inverted (PIN) architecture.
• Conducted outdoor performance testing with bandpass filters.

Main Results:

• Achieved photodetectors with 75% external quantum efficiency and low dark current (1 μA/cm²).
• CQD photodetectors with a 1370 nm filter showed 140x higher signal-to-background ratio than Si detectors at 1 μW/cm².
• Demonstrated superior outdoor performance compared to traditional silicon detectors.

Conclusions:

• Surface-ligand engineering is effective for optimizing CQD photodetector performance.
• 1370 nm-operating CQD photodetectors are a promising alternative to Si for outdoor infrared depth imaging.
• CQD photodetectors offer significant advantages in signal-to-background ratio for real-world applications.