Ultranarrow-bandgap small-molecule acceptor enables sensitive SWIR detection and dynamic upconversion imaging

Area of Science:

• Organic electronics
• Optoelectronics
• Materials science

Background:

• Short-wavelength infrared (SWIR) light detection is crucial for many technologies.
• Organic semiconductors offer a path to cost-effective, flexible, and large-area SWIR photodiodes.
• Current SWIR organic photodiodes face limitations in spectral responsivity and specific detectivity due to poor exciton dissociation and high noise.

Purpose of the Study:

• To synthesize a novel SWIR organic semiconductor.
• To fabricate and optimize SWIR organic photodiodes (OPDs) for enhanced performance.
• To demonstrate the application of these OPDs in SWIR-to-visible imaging.

Main Methods:

• Synthesis of a new small molecule for SWIR detection.
• Fabrication of OPDs with optimized exciton dissociation, charge injection, and SWIR transmittance.
• Integration of SWIR OPDs into all-organic upconversion devices for imaging.

Main Results:

• The synthesized SWIR small molecule covers 0.3 to 1.3 micrometers, peaking at 1100 nm.
• The optimized photodiode achieved a record spectral responsivity of 0.53 A/W and specific detectivity of 1.71 × 10^13 Jones at 1110 nm.
• The specific detectivity in the 1 to 1.2 micrometer range exceeded that of uncooled commercial InGaAs photodiodes.
• All-organic upconversion devices demonstrated static and dynamic SWIR-to-visible imaging with high efficiency and resolution.

Conclusions:

• The developed organic semiconductor significantly advances SWIR detection capabilities.
• Optimized organic photodiodes offer competitive or superior performance compared to existing technologies.
• The integration into upconversion devices opens new avenues for SWIR imaging applications.