Can an ink-based quantum dot SWIR photodiode maintain its electrical performance for more than 500 hours at 90 °C?
Our latest INFIQ® results show that it can.
A 1550 nm INFIQ® ink-based photodiode maintained stable dark current, stable current under illumination and consistent current-voltage behaviour throughout 504 hours of thermal ageing at 90 °C.
For SWIR developers, this is an important milestone. Emerging materials must perform well initially, but more importantly they must also retain that performance through the thermal stresses associated with device processing, packaging and operation.
504 hours at 90 °C | Stable dark current | Stable illuminated current | Consistent J-V behaviour
Why thermal stability matters for SWIR photodiodes
Colloidal quantum dot photodiodes are attracting growing interest in short-wave infrared imaging and sensing because they combine wavelength tunability, strong absorption and compatibility with scalable integration approaches.
However, commercial adoption depends on more than initial device performance. Sensor materials and device stacks must remain stable during downstream processing, packaging, storage and operation. Elevated temperature can expose weaknesses in leakage control, interfaces and charge transport, making thermal ageing an important step in technology development.
500-hour thermal ageing at 90 °C
Quantum Science has developed a 1550nm INFIQ® ink-based photodiode and subjected it to continuous thermal ageing at 90 °C, with electrical performance monitored at regular intervals.
• Stable dark current: At -1 V reverse bias, there was no progressive increase in leakage through the 504-hour test.
• Stable current under illumination: The device maintained its photoresponse without a clear deterioration over time.
• Consistent current-voltage behaviour: Full J-V measurements after 115, 210, 336 and 504 hours remained closely aligned, particularly across the reverse-bias operating region.
What defines good photodiode stability?
Photodiode stability is not defined by a single measurement. Dark current indicates whether reverse-bias leakage remains controlled; current under illumination reflects retention of photoresponse; and consistent J-V curves show whether the broader device behaviour remains intact.
Taken together, the three measurements provide complementary evidence that the INFIQ® device retained stable electrical behaviour under prolonged thermal stress. This is an important milestone within the wider INFIQ® reliability programme.
Scalable processing must also be reliable
Ink-based processing offers a practical route towards scalable quantum dot integration. In a pre-formulated ink, the quantum dots and their surface chemistry are engineered before coating, creating the potential for simpler deposition, efficient material use and compatibility with different substrates and device formats.
The challenge is that the complete formulation and device stack must work together. The ink must remain stable during handling, form a uniform and electronically functional film, interact correctly with adjacent layers and retain its performance after fabrication.
The 504-hour result therefore demonstrates the combined stability of the ink-derived film, charge-transport layers, interfaces and overall photodiode architecture under the tested conditions.
Combining scalability and reliability in ink-based quantum dot photodiodes
Quantum Science is developing INFIQ® as an infrared materials and device-stack platform, combining quantum dot synthesis, ink formulation, film processing, interface engineering, stack development, reliability testing and integration support.
For sensor developers, ROIC partners and camera companies, these data provide a stronger basis for progressing from material evaluation into device-stack integration and joint development. They reduce one important technical uncertainty on the path towards next-generation SWIR imaging and sensing systems.
Testing is now progressing towards longer durations and a broader range of reliability conditions as part of the continued development and qualification of the INFIQ® platform.
Evaluating quantum dot technology for your next SWIR platform?
Speak with Quantum Science about INFIQ® ink evaluation, device-stack integration and joint-development programmes at info@qscis.com or through our contact page.