A research team led by Professor Sohee Jeong at Sungkyunkwan University has uncovered a key chemical pathway for the controlled synthesis of III–V semiconductor quantum dots, a class of next-generation infrared materials expected to play an important role in autonomous driving sensors, smart sensing systems, night-vision devices, and short-wave infrared optoelectronics.
The study was conducted in close international collaboration with Professor Maksym V. Kovalenko’s group (SIEST faculty) at ETH Zurich and was published in the Journal of the American Chemical Society under the title “Metal–Amide Chemistry Enables Controlled Heavy-Pnictogen Reduction for Colloidal III–V Nanocrystal Synthesis.”
As infrared-based technologies become increasingly important in daily life, including nighttime object recognition for autonomous vehicles and smart home devices, the demand for high-performance infrared semiconductor materials continues to grow. III–V semiconductor quantum dots such as indium arsenide and indium antimonide have attracted attention for their excellent infrared optical properties and their potential as less toxic, Pb- and Hg-free material platforms. However, the lack of practical precursor systems for heavy-pnictogen (As and Sb) and limited understanding of their underlying precursor chemistry have restricted broader synthetic design and scalability.
To address this challenge, Professor Jeong’s team decoupled the activation of heavy-pnictogen(III) precursors from quantum dot formation. Through this approach, the researchers were able to observe how heavy-pnictogen(III) precursors are reduced and gain reactivity before forming nanocrystals.
The team found that metal–amide species formed from metal–alkyl reagents and primary amines play a central role in controlling the reduction of heavy-pnictogen(III) precursors. In particular, the study revealed that these metal–amide complexes undergo thermally activated amide-to-imine oxidation and mediate the reduction of heavy-pnictogen precursors. By adjusting the reduction temperature and metal-cation environment, the researchers could access partially reduced precursor states suitable for III–V nanocrystal synthesis.
This finding marks a step toward moving from empirical synthesis toward a chemistry-based design strategy. Rather than adding all reactants at once and relying on trial-and-error optimization, the new approach enables researchers to prepare precursors with controlled reactivity in advance and then use them for nanocrystal growth.
Using this strategy, the team successfully synthesized indium arsenide and indium antimonide nanocrystals without adding extra reducing agents during the nanocrystal growth step. This compatibility with pre-reduced precursors allows the synthesis to be adapted to various platforms, including heat-up, hot-injection, and continuous-injection methods, offering greater flexibility for scalable nanocrystal production.
The work systematically reveals a chemical mechanism hidden within a complex semiconductor synthesis process. It demonstrates how fundamental chemical principles can guide the design of advanced materials for technologies such as autonomous driving sensors and night-vision cameras.
This study is significant in that it establishes a rational precursor design principle for heavy-pnictogen-based III–V nanocrystals. The findings are expected to contribute to the development of safer, more reproducible, and more scalable infrared semiconductor materials for next-generation smart sensors, imaging systems, and optoelectronic devices.
The research was supported by the Ministry of Science and ICT, the National Research Foundation of Korea, Samsung Electronics, and related research infrastructure programs.