Quad-Band Short-Wave Infrared Detection Using Bandgap-Controlled Ag2Te Quantum Dots
Se Young Park a, Shlok Joseph Paul b, Zheng Li b, Seongjae Lee a, Yong Hyun Jo a, Eunsoo Hong a, Hyunwoo Jo a, Yongnam Ahn c, Haoxian Zheng b, Joo Hyung Kim d, Ayaskanta Sahu b, Moon Sung Kang a
a Department of Chemical and Biomolecular Engineering, Sogang University, Seoul 04107, Republic of Korea
b Department of Chemical and Biomolecular Engineering, Tandon School of Engineering, New York University, Brooklyn, New York 11201, United States
c Department of Chemical and Biological Engineering, Korea University, Seoul 02841, Republic of Korea
d Imec, Leuven, 3001, Belgium
Proceedings of Emerging Light Emitting Materials 2025 (EMLEM25)
La Canea, Greece, 2025 October 8th - 10th
Organizers: Maksym Kovalenko and Grigorios Itskos
Poster, Se Young Park, 070
Publication date: 17th July 2025

Multispectral photodetection in the short-wave infrared (SWIR) range has been highly desirable for applications such as night vision, quality inspection, and bio-imaging. Colloidal quantum dots (QDs) have been extensively explored as a promising alternative to conventional epitaxial semiconductors for multispectral photodetection owing to their size-tunable bandgap-controlled optoelectronic properties and potential for low-cost, high-throughput fabrication. Here, a multispectral SWIR photodetector is demonstrated based on four distinct sizes of heavy-metal-free Ag2Te QDs, each patterned side-by-side using a direct QD photopatterning process- involving QD film deposition, ultraviolet-induced selective QD ligand crosslinking, and pattern development. This enables precise spatial integration of the four different QD channels into a single device platform that is independently addressible, allowing integrated multispectral SWIR detection within a monolithic platform. The resulting multispectral Ag2Te QD channels show maximum responsivities of 188.4, 173.5, 155.6, and 185.8 mA W−1 at 1150, 1350, 1550, and 1800 nm, respectively. By leveraging the distinct photoresponses of four spectrally differentiated Ag2Te QD channels to SWIR input light, it is demonstrated that the multispectral photodetector enables simple, non-spectrometric wavelength identification—highlighting a unique capability unattainable with conventional single-size-QD devices.

This work was supported by the Sogang University Research Grant of 2024 (202412021.01), the National Research Foundation of Korea (NRF) grant funded by the Ministry of Science, ICT (2021R1A2C2008332, RS-2024-00445116), and the Office of Naval Research (ONR) grant (N00014-20-1-2231, N00014-24-1-2683).

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