Researchers in South Korea have developed a next-generation sensor material that can detect a broad spectrum of light, from visible wavelengths to the long-wave infrared range, in a single device. This breakthrough paves the way for simpler, more robust, and multifunctional optical sensors for a wide array of applications, including autonomous vehicles, security systems, and consumer electronics. The new material is not only more versatile than existing technologies but can also be produced cost-effectively on a large scale.
The joint research team, led by Dr. Wooseok Song of the Korea Research Institute of Chemical Technology (KRICT) and Professor Dae Ho Yoon at Sungkyunkwan University, engineered a material that solves a fundamental limitation of current photodetectors. Previously, separate sensors were required to detect different light bands, such as visible, near-infrared, and long-wave infrared, which made integrated devices complex and bulky. This new technology integrates these functions into a single, thin, and lightweight material that maintains high stability even in harsh environmental conditions, including high temperatures and humidity.
Expanding the Spectrum of Light Detection
Modern imaging and sensing systems often need to perceive more than what the human eye can see, tapping into the infrared spectrum to detect thermal signatures or navigate in low-light conditions. However, this has traditionally required multiple sensors. For instance, an autonomous vehicle might use one type of sensor for visible light cameras and another for thermal imaging. The Korean team’s photodetector unifies this capability into one component. The material achieves broadband detection over a range approximately eight times wider—from 0.5 to 9.6 micrometers—than conventional 2D semiconductor sensors, which are limited to a range of about 0.4 to 1.2 micrometers. This allows a single sensor to perform functions that previously required several distinct parts, streamlining device design and performance.
A Novel Material and Its Properties
The core of the innovation is a new material classified as a topological crystalline insulator (TCI). The researchers created this material by taking a 2D semiconductor, tin selenide (SnSe), and substituting a small amount of tellurium into its structure. As a quantum material, TCIs have a narrow band gap, a characteristic that is crucial for detecting low-energy photons found in the mid- and long-wave infrared portions of the spectrum. This property overcomes the limitations of typical 2D semiconductors, which have wider band gaps and cannot sense this type of light. The unique TCI structure allows electrons to move without resistance across the material’s surface, which enables highly sensitive and rapid detection of light across the entire target spectrum. This includes the ability to sense subtle thermal radiation, such as the heat emitted by a human finger.
Breakthrough in Manufacturing and Scalability
A significant advantage of this new photodetector is its potential for low-cost, large-scale production. Synthesizing high-quality TCI materials has historically required expensive and complex ultra-high-vacuum equipment, such as molecular beam epitaxy (MBE) systems, which are not suited for mass manufacturing. The research team developed a much simpler and more cost-efficient method using a solution-based thermal decomposition process. This technique allowed them to produce a uniform layer of the material on a 6-inch silicon wafer, a standard size used in the semiconductor industry. This compatibility with existing fabrication processes is a critical step toward commercialization. The team is already working to scale the technology to 8-inch wafers and beyond. The material’s resilience is another key manufacturing and practical advantage; it remains stable even when submerged in water.
Real-World Applications and Future Prospects
The potential applications for this unified sensor are extensive and varied. Its ability to detect both visible light and thermal signatures in a single, compact package makes it ideal for advanced driver-assistance systems in cars and for sophisticated imaging systems in military drones. In consumer electronics, it could lead to more capable sensors in smartwatches or enhance the functionality of home security systems based on the Internet of Things (IoT). Because the material is thin, stable, and sensitive, it could also open new avenues for medical imaging and environmental monitoring. Looking forward, the researchers plan to integrate the material into complete sensor modules by developing sensor arrays and integrated circuits. This work aims to replace expensive imported sensors with high-performance, domestically produced alternatives, marking a significant step for the sensor industry. The team’s research was published in the journal ACS Nano.
