Quantum Science demonstrates a 2400 nm PbS quantum dot platform for scalable, ITAR-free extended-SWIR development
Interest in infrared sensing is moving beyond 1.7 µm. While visible-to-SWIR imaging is already established in industrial inspection, machine vision and material identification, many materials show stronger and more distinct spectral features at longer wavelengths. Plastics, organics, liquids and chemicals are clearer to differentiate in the 1.7 to 2.5 µm range, making this region increasingly relevant for sensing system design.
Access to this range remains constrained. Extended-InGaAs can operate here, but performance trade-offs become more pronounced as wavelength increases. Dark current rises, cooling requirements increase, costs scale up, and format and supply chain constraints become harder to manage.
Quantum Science is addressing this gap through INFIQ®, its infrared quantum dot technology platform.
INFIQ® is QS’s broader platform for infrared quantum dot materials, inks, films, device stacks and integration pathways. It is designed to support sensing opportunities from SWIR into eSWIR and beyond.
The latest milestone is QS’s 2400 nm PbS quantum dot platform for extended-SWIR detection – the best performance in the eSWIR range achieved in the industry to date. QS has taken this material from synthesis through to ink formulation and into working photodiode devices, with measured response extending to 2.5 µm. This shows that long-wavelength quantum dots can be carried through the stages that matter for OEM adoption, from material through to device-level performance and integration considerations.
Why eSWIR Matters for OEMs
For OEMs, camera companies and system developers, the 2.0 to 2.5 µm range provides access to spectral information that is less visible in standard SWIR systems. This has practical implications across plastics sorting, food inspection, moisture detection, pharmaceutical analysis, industrial process monitoring and advanced manufacturing.
Deploying sensors in this range requires more than spectral coverage alone. System-level considerations such as cooling, noise, detector format, integration pathways and supply chain control all influence adoption. Any viable platform needs to address these factors alongside wavelength performance.
INFIQ® has been developed with those constraints in mind, with a focus on manufacturable formats and compatibility with future camera architectures.
A Different Route into 2.5 µm Detection
PbS quantum dots offer a fundamentally different route to extended-SWIR sensing.
They are a wavelength-tunable material system that can be processed in solution. This allows them to be deposited as thin films and incorporated into photodiode structures. The approach also supports the possibility of integration with semiconductor readout technologies over time.
From a supply perspective, the platform offers an ITAR-free route, which is relevant for programmes that require fewer export restrictions and greater control over sourcing.
QS’s 2400 nm PbS QD work demonstrates this route in action. The platform starts with controlled synthesis of long-wavelength PbS nanomaterials, converts them into an ink suitable for deposition, and builds photodiode devices that show extended-SWIR response.
Transmission electron microscopy shows the nanoscale morphology of QS’s long-wavelength PbS QD material platform.
QS’s 2400 nm PbS QD material is processed into an ink form factor for thin-film and photodiode development.
The 2400 nm QD photodiode demonstrates extended-SWIR response into the 2.5 µm region, showing QS’s ability to translate long-wavelength PbS QD materials into working photodiode devices.
eSWIR Performance Considerations
In eSWIR detection, wavelength response is only part of the story. Dark current is equally important because it directly affects noise, cooling requirements and system-level complexity.
QS’s 2400 nm QD photodiodes have shown dark-current density in the ~10 µA/cm² range at -1 V. While EQE optimisation remains an active development focus, this low-dark-current profile points towards a differentiated performance architecture for eSWIR sensing. Compared with representative commercial extended-InGaAs photodiodes under reverse-bias operation, this corresponds to approximately 10³–10⁴ lower dark-current density.
This points to a platform that can be tuned at both material and device level to meet specific application requirements, rather than following a fixed performance envelope.
From Proof Point to Joint Development
The 1.7-2.5 µm region contains valuable material information, but today’s detector options remain constrained by cost, cooling, dark current, format and supply-chain complexity.
INFIQ® is being positioned as a practical route into this region. The 2400 nm work demonstrates that long-wavelength PbS quantum dots can be processed, integrated and measured in device form, with performance characteristics that are relevant for system design.
QS is now working with selected OEMs, ROIC developers, camera companies and system integrators on structured development programmes. These collaborations focus on ink evaluation, device stack design, integration alignment and application-specific demonstrators.
Development beyond 1.7 µm is gaining attention across multiple sectors. INFIQ® is being built to support that shift with a platform that can move from material through to system-level implementation.