Design, preparation and characterization of mixed semiconductor nanocrystal-salt crystals as extremely photostable and highly efficient light emitting materials for optical applications

• Applicants: Professor Dr. Alexander Eychmüller; Dr. Ute Resch-Genger
• Subject Area: Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: from 2010 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 187261748

• Final Report Year: 2020

Final Report Abstract

In the framework of this project, a variety of colloidal nanocrystals was investigated regarding their compatibility with the salt matrices. The salts were chosen to provide an environmental stability to the nanocrystals, especially if the degradation reactions involving atmospheric oxygen are considered. Moreover, the encapsulated nanocrystals can be further processed by combining them with organic polymers to reach additional protection from the humidity and the processability, which is inherent to many polymers. Among the nanocrystals both “classical” toxic metals containing (CdSe, CdTe, PbSe etc.) and potentially friendlier materials (Ag-In-S, Cu-In-S. etc.) were investigated in depth. Very promising results were achieved with the encapsulation into most abundant salts, such as NaCl and KCl. Moreover, the latter was shown to be compatible with newly developed embedding procedure utilizing a cold flow phenomenon. The salt pellets obtained by the cold flow can embed not only the nanocrystals originally mixable with the saturated salt media, but also those compatible solely with organic solutions (e.g. prepared by the so-named hot-injection synthesis) or extremely unstable materials (e.g. perovskite nanoparticles). The applicability of the nanocrystals embedded to salts as strong and stable emitters, e.g. for LED applications was demonstrated in the variety of device-architectures.

Publications

• Cold Flow as Versatile Approach for Stable and Highly Luminescent Quantum Dot–Salt Composites. ACS Appl. Mater. Interf. 2016, 8, 21570-21575
  Benad, A.; Guhrenz, C.; Bauer, C.; Eichler, F.; Adam, M.; Ziegler, C.; Gaponik, N.; Eychmüller, A.
  
• Colloidal Nanocrystals Embedded in Macrocrystals: Methods and Applications. J. Phys. Chem. Lett. 2016, 7 (20), 4117-4123
  Adam, M.; Gaponik, N.; Eychmüller, A.; Erdem, T.; Soran-Erdem, Z.; Demir, H. V.
  
• Solid-State Anion Exchange Reactions for Color Tuning of CsPbX3 Perovskite Nanocrystals. Chem. Mater. 2016, 28, 9033-9040
  Guhrenz, C.; Benad, A.; Ziegler, C.; Haubold, D.; Gaponik, N.; Eychmüller, A.
  
• Synthesis of NIR-Emitting InAs-Based Core/Shell Quantum Dots with the Use of Tripyrazolylarsane as Arsenic Precursor. Particle & Particle Systems Characterization 2018, 35 (9), 1800175
  Tietze, R.; Panzer, R.; Starzynski, T.; Guhrenz, C.; Frenzel, F.; Würth, C.; Resch-Genger, U.; Weigand, J. J.; Eychmüller, A.
  
• Brightly Luminescent Cu-Zn-ln-S/ZnS Core/Shell Quantum Dots in Salt Matrices. Z. Phys. Chem. 2019, 233 (1), 23-40
  Lox, J. F. L.; Eichler, F.; Erdem, T.; Adam, M.; Gaponik, N.; Demir, H. V.; Lesnyak, V.; Eychmüller, A.
  
• Photoluminescence of Ag-In- S/ZnS quantum dots: Excitation energy dependence and low-energy electronic structure. Nano Research 2019, 12, 1595-1603
  Martynenko, I. V.; Baimuratov, A. S.; Weigert, F.; Soares, J. X.; Dhamo, L.; Nickl, P.; Doerfel, I.; Pauli, J.; Rukhlenko, I. D.; Baranov, A. V.; Resch-Genger, U.
  
• Rationally Designed Synthesis of Bright AgInS2/ZnS Quantum Dots with Emission Control, Nano Research 2020, online
  Soares, J. X.; Wegner, K. D.; Ribeiro, D. S. M.; Melo, A.; Santos, J. L. M.; Resch-Genger, U.