Implementation of high-quality warm-white light-emitting diodes by a model-experimental feedback approach using quantum dot-salt mixed crystals
| Autor: | Gordon M. Stachowski, Marcus Adam, Hilmi Volkan Demir, Josephine F. L. Lox, Nikolai Gaponik, Talha Erdem, Alexander Eychmüller, Christoph Bauer, Zeliha Soran-Erdem, Jan Poppe |
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| Přispěvatelé: | Demir, Hilmi Volkan |
| Jazyk: | angličtina |
| Rok vydání: | 2015 |
| Předmět: |
Materials science
White LEDs Correlated color temperature Chemical and physical properties White LED Ionic bonding Mixed crystals Color 02 engineering and technology High color rendering index 010402 general chemistry 01 natural sciences 7. Clean energy law.invention Matrix (chemical analysis) chemistry.chemical_compound law Ionic strength Borate minerals Semiconductor quantum dots General Materials Science Solubility Crystallization Sodium borate Color conversions Color conversion Lighting Diode Composites Optical properties business.industry Borax Quantum dots Composite materials White light emitting diodes 021001 nanoscience & nanotechnology Diodes Light emitting diodes 0104 chemical sciences Nanocrystals chemistry Quantum dot Colloidal nanocrystals Optoelectronics 0210 nano-technology business |
| Zdroj: | ACS Applied Materials and Interfaces |
| Popis: | In this work, a model-experimental feedback approach is developed and applied to fabricate high-quality, warm-white light-emitting diodes based on quantum dots (QDs) as color-conversion materials. Owing to their unique chemical and physical properties, QDs offer huge potential for lighting applications. Nevertheless, both emission stability and processability of the QDs are limited upon usage from solution. Incorporating them into a solid ionic matrix overcomes both of these drawbacks, while preserving the initial optical properties. Here borax (Na2B4O7·10H2O) is used as a host matrix because of its lower solubility and thereby reduced ionic strength in water in comparison with NaCl. This guarantees the stability of high-quality CdSe/ZnS QDs in the aqueous phase during crystallization and results in a 3.4 times higher loading amount of QDs within the borax crystals compared to NaCl. All steps from the synthesis via mixed crystal preparation to the warm-white LED preparation are verified by applying the model-experimental feedback, in which experimental data and numerical results provide feedback to each other recursively. These measures are taken to ensure a high luminous efficacy of optical radiation (LER) and a high color rendering index (CRI) of the final device as well as a correlated color temperature (CCT) comparable to an incandescent bulb. By doing so, a warm-white LED with a LER of 341 lm/Wopt, a CCT of 2720 K and a CRI of 91.1 is produced. Finally, we show that the emission stability of the QDs within the borax crystals on LEDs driven at high currents is significantly improved. These findings indicate that the proposed warm-white light-emitting diodes based on QDs-in-borax hold great promise for quality lighting. © 2015 American Chemical Society. |
| Databáze: | OpenAIRE |
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