Dark Current Reduction Strategy via a Layer-By-Layer Solution Process for a High-Performance All-Polymer...

Area of Science:

• Organic electronics
• Photodetector technology
• Materials science

Background:

• High-performance organic photodetectors require specific bulk-heterojunction morphologies to minimize leaking current.
• Vertically gradient structures are preferred for suppressing dark current in organic photodetector designs.

Purpose of the Study:

• To demonstrate an all-polymer photodetector featuring a segregated bulk-heterojunction active layer.
• To investigate the impact of this structure on photodetector performance, particularly dark current and specific detectivity.

Main Methods:

• Fabrication of an all-polymer photodetector using a layer-by-layer solution process.
• Characterization of the photodetector's active layer morphology as a segregated bulk-heterojunction.
• Measurement of dark current density, responsivity, and specific detectivity.

Main Results:

• The all-polymer photodetector exhibited a dramatically reduced dark current density due to a built-in charge blocking layer.
• Achieved responsivity of 0.25 A/W at ~600 nm.
• Calculated specific detectivity of 5.68 × 10^12 cm Hz^1/2 W^-1 at 1 kHz.

Conclusions:

• The segregated bulk-heterojunction in an all-polymer photodetector effectively suppresses dark current.
• The demonstrated photodetector shows among the best performances for polymer-based devices.
• This approach offers a facile method for enhancing polymer photodetector specific detectivity.