Multiband infrared focal plane arrays (FPAs) have broad applications in remote sensing, environmental monitoring, military security, medical diagnostics, food safety detection, and other fields. However, current multiband detectors face several challenges that hinder their widespread adoption and development. Traditional multiband detection systems typically rely on combining multiple single-band detectors to capture spectral information across various wavelengths. These systems are often bulky, require complex optical designs, and involve multiple detection modules, which leads to high costs and low integration. Furthermore, single-band detectors made from materials like HgCdTe, InSb, and InGaAs, while offering high sensitivity and low noise, have limited wavelength ranges and are difficult to tune. As a result, the flexibility and performance enhancement potential of these detectors are constrained.

With the increasing demand for smaller, more integrated, and more cost-effective devices, the size and complexity of traditional multiband infrared detectors have become major obstacles. The current designs fail to meet the requirements for compact, efficient, and flexible multiband detection systems. Therefore, there is an urgent need for new technologies that can not only cover multiple infrared wavelength ranges but also offer high integration, simplified optical design, and cost reduction. Advancing such technologies will enable infrared detectors to expand into a broader range of applications and accelerate the development of infrared sensing technologies.

Recent advancements in colloidal quantum dot technology have significantly enhanced the performance and capabilities of multiband infrared FPAs. Key innovations include the development of novel methods for quantum dot synthesis, such as the use of bulk quantum dot coupling, heterojunction bandgap engineering, and planar stacking. These methods allow for the precise control of the quantum dot size and the engineering of their energy band structures, which in turn influence their absorption spectra. Through these techniques, colloidal quantum dots (CQDs) can be designed to respond to a wide range of infrared wavelengths, from the short-wave infrared (SWIR) to the mid-wave infrared (MWIR) regions. Additionally, the integration of optical filters within the device architecture further enhances spectral resolution. Notably, CQDs exhibit high quantum efficiency and tunability, which enable the development of compact, integrated multiband detectors capable of operating across a broad spectral range. The fabrication process of these CQD-based FPAs typically involves the deposition of quantum dot layers via solution-based methods such as spin-coating or inkjet printing, which are both cost-effective and scalable. Moreover, the development of self-assembled monolayers and the incorporation of novel substrates have contributed to the improvement of the mechanical stability and operational lifespan of these detectors. Recent research has also focused on optimizing the electronic properties of CQDs through doping and surface modifications, aiming to further enhance their spectral responsiveness and detectivity.

The future of multiband colloidal quantum dot infrared FPAs looks promising, with ongoing efforts to overcome existing challenges related to stability, scalability, and integration into practical systems. The flexibility in spectral tuning offered by CQDs allows for their potential use in a variety of applications, from high-precision environmental monitoring to defense-related infrared imaging. Future research will likely focus on improving the uniformity of the CQD films, enhancing their sensitivity at lower wavelengths, and developing methods for large-scale production. In conclusion, multiband CQD-based infrared FPAs represent a significant step forward in the miniaturization and performance enhancement of infrared detection systems. With continued advancements in material synthesis, fabrication techniques, and system integration, these devices are poised to revolutionize a wide array of industrial and scientific applications.