Eco-Friendly, High-Performance Short Wave Infrared (SWIR) Quantum Dot Emitters

Colloidal quantum dots (CQDs) that absorb and emit in the short-wave infrared (SWIR, 0.9–1.7 μm) region are critically important in optoelectronics (e.g., SWIR-based LEDs, lasers, photodetectors, telecommunication) and biological imaging. However, SWIR CQD LEDs often underperform due to the low photoluminescence quantum yield (PLQY) of the QDs. Furthermore, many efficient SWIR active QDs demonstrated in application¹ are based on heavy metals such as lead (Pb), cadmium (Cd), and mercury (Hg), which are highly toxic and subject to RoHS (Restriction of Hazardous Substances ) regulatory restrictions for consumer electronics applications. This emphasizes the critical need for the development of more SWIR-efficient, environmentally friendly QDs to replace conventional Cd/Pb/Hg-based QDs in various applications.
In my presentation, I will explore the potential of I-III-VI-based nanocrystals, particularly Cu/Ag-In-Se, as eco-friendly alternatives to toxic heavy metal-based QDs². Specifically, I will discuss the development of Cu-In-Zn-Se/ZnS (CIZSe-ZnS) core-shell QDs that emit in the SWIR range. I will detail our synthetic methodologies that enable precise modulation of composition and size tunability, facilitating targeted monitoring of PL emission over a wide range from 915 nm to 1230 nm. To enhance the biocompatibility and chemical stability of the material, we passivated the QDs’ surfaces with amorphous alumina (CIZSe/ZnS/Al₂O₃). This surface passivation not only ensures environmental and photostability but also enhances the PLQY. Notably, we achieved a PLQY of 53% at 1050 nm and 20% at 1230 nm, similar to the highest reported to date from heavy metal-free QDs in this range. Unlike other indium-based multinary core-shell QDs (e.g., CuInS₂/ZnS) or III-V based (InAs/InSb) QDs, these nanocrystals exhibit a narrow PL full width at half maximum (FWHM) of 102 meV, comparable to PbSe nanoplatelets. Finally, I will demonstrate the application of these QDs as efficient SWIR-LEDs, underscoring their practical utility and potential for advancing optoelectronic technologies.

References:
(1) Pradhan, S.; Di Stasio, F.; Bi, Y.; Gupta, S.; Christodoulou, S.; Stavrinadis, A.; Konstantatos, G. Nature Nanotech 2019, 14, 72.
(2) Bora, A.; Lox, J.; Hübner, R.; Weiß, N.; Bahmani Jalali, H.; di Stasio, F.; Steinbach, C.; Gaponik, N.; Lesnyak, V. Chem. Mater. 2023, 35, 4068.