Silver telluride colloidal quantum dot
infrared photodetectors and image sensors
【Highlights】
- With the thriving development of drones, night vision devices, and medical imaging, the demand for infrared detection and imaging continues to increase. In particular, silver telluride colloidal quantum dots have recently garnered significant attention from both the research community and industry due to their broad tunability and low cost. In this paper, the authors review the latest research advances of silver telluride quantum dots in infrared photodetectors and image sensors, as well as discuss future directions. The authors provide an in-depth discussion on the working principles, materials optimization, and fabrication techniques of such devices, while also elucidating their broad application prospects. It is believed that this paper will offer important technical summaries and outlooks for R&D professionals in the optoelectronics and sensing fields.
Results
Shortwave infrared (SWIR) imaging is crucial for applications like night vision, food safety inspection, and medical diagnosis. However, existing SWIR sensors often rely on toxic materials like indium gallium arsenide or mercury cadmium telluride. This paper presents a novel SWIR sensor technology based on environmentally-friendly quantum dots made from copper, indium, sulfur, and zinc. These non-toxic quantum dots are synthesized via a scalable solution-processed method, enabling high-performance and cost-effective SWIR imaging.
The researchers demonstrate SWIR photodetectors from quantum dots with tunable emission spanning 1000-1700 nm by adjusting their size and composition. Prototype sensors achieve excellent performance metrics: specific detectivity up to 1×10^13 Jones, optical responsivity beyond 0.4 A/W, and fast temporal response sub-30 microseconds. This matches and even exceeds current indium gallium arsenide and mercury cadmium telluride sensors while avoiding their intrinsic toxicity issues.
Imaging experiments verify that the quantum dot SWIR sensors can capture high-quality videos in low-light environments and through obscuring barriers like fog. They can also detect microscopic features and compositional variations in food and biological samples via hyperspectral imaging, showcasing exciting applications in food safety, biotechnology, and medical diagnosis. This transformative technology provides a safe, scalable path to democratizing life-changing SWIR imaging technology.
References:
Supplementary Figure 9. Optical transfer matrix method (TMM) simulation of the device absorption with various AgBiS2 NC layer thicknesses. Device structure is Glass/ITO(100 nm)/SnO2(20 nm)/AgBiS2(–)/Ag2Te 85 nm/Au(100 nm). The internal quantum efficiency was assumed as 100%. Thus, here the EQE indicates the total absorption in both AgBiS2 and Ag2Te layers. The peak shift can be attributed to the Fabry-Perot cavity effect.
Supplementary Figure 16. Dark current fitting of devices without and with AgBiS2 NCs as interface layer. Device without AgBiS2 NC interface layer showed significantly higher non-Ohmic leakage current, which dominates the reverse bias region.
