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HL: Fachverband Halbleiterphysik

HL 20: Poster I

HL 20.48: Poster

Dienstag, 10. März 2026, 18:00–20:00, P1

RoHS-Compliant Nanocrystal LEDs for Flexible Near-Infrared Biomedical Emitters — •Simon Letzer¹, Andrey Iodchik², Rabiul Islam¹, Vladimir Lesnyak², and Caroline Murawski¹ — ¹Institute of Solid State Electronics, TU Dresden, Germany — ²Physical Chemistry, TU Dresden, Germany

The near-infrared (NIR) biological window enables deep-tissue access for non-invasive imaging and health monitoring. Wearable emitters for this range require flexible and efficient materials, yet organic LEDs lose performance above 850 nm. Colloidal nanocrystals (NCs) offer a promising alternative for NIR emission, although most efficient systems contain Hg, Cd, or Pb, restricting their use in biomedical settings. We therefore investigate RoHS-compliant NCs for solution-processed NIR emitters. As a baseline, we employed CdHgSe/CdZnS core/shell NCs, which have already demonstrated strong performance in LEDs and provide a reliable platform for optimizing device processing [1]. Film quality is strongly influenced by concentration, solvent, dispense time, spin profile, and baking conditions. High-boiling-point solvents produced uniform macroscopic films, while low-temperature baking and high spin speeds improved nanoscale smoothness. Building on these conditions, we fabricated our first RoHS-compliant devices based on CuInS2/ZnS NCs. Processing parameters were refined for this material, and different transport layers and device architectures were evaluated. These results demonstrate a viable path toward cadmium-free NIR emitters for wearable biomedical sensors.

[1] Adv. Funct. Mater. 2024, 34, 2310067.

Keywords: Nanocrystals; Near-infrared; LEDs; Thin films; Flexible devices