Red Mn4+-doped fluoride phosphors: Why purity matters
| Autor: | Dirk Poelman, Reinert Verstraete, Jonas Joos, Philippe Smet, Heleen Sijbom, Katleen Korthout, Christophe Detavernier |
|---|---|
| Přispěvatelé: | Schanze, Kirk |
| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
Materials science
LEDs Inorganic chemistry LIGHT-EMITTING-DIODES LUMINESCENCE PROPERTIES Phosphor 02 engineering and technology Color temperature 010402 general chemistry 01 natural sciences law.invention SYNCHROTRON-RADIATION chemistry.chemical_compound PHOTOLUMINESCENCE PROPERTIES law purity WARM-WHITE LEDS CRYSTAL-STRUCTURE General Materials Science Incandescent light bulb K2SIF6MN4+ PHOSPHOR fluoride phosphors OPTICAL-PROPERTIES stability 021001 nanoscience & nanotechnology Hydrogen fluoride THERMAL-DECOMPOSITION 0104 chemical sciences Color rendering index Chemistry CONVERSION PHOSPHORS Physics and Astronomy chemistry transition-metal dopants 0210 nano-technology Luminous efficacy Fluoride Light-emitting diode |
| Zdroj: | 'ACS Applied Materials & Interfaces ', vol: 10, pages: 18845-18856 (2018) ACS APPLIED MATERIALS & INTERFACES |
| ISSN: | 1944-8244 |
| Popis: | Traditional light sources, e.g., incandescent and fluorescent lamps, are currently being replaced by white light-emitting diodes (wLEDs) because of their improved efficiency, prolonged lifetime, and environmental friendliness. Much effort has recently been spent to the development of Mn4+-doped fluoride phosphors that can enhance the color gamut in displays and improve the color rendering index, luminous efficacy of the radiation, and correlated color temperature of wLEDs used for lighting. Purity, stability, and degradation of fluoride phosphors are, however, rarely discussed. Nevertheless, the typical wet chemical synthesis routes (involving hydrogen fluoride (HF)) and the large variety of possible Mn valence states often lead to impurities that drastically influence the performance and stability of these phosphors. In this article, the origins and consequences of impurities formed during synthesis and aging of K2SiF6:Mn4+ are revealed. Both crystalline impurities such as KHF2 and ionic impurities such as Mn3+ are found to affect the phosphor performance. While Mn3+ mainly influences the optical absorption behavior, KHF2 can affect both the optical performance and chemical stability of the phosphor. Moisture leads to decomposition of KHF2, forming HF and amorphous hydrated potassium fluoride. As a consequence of hydrate formation, significant amounts of water can be absorbed in impure phosphor powders containing KHF2, facilitating the hydrolysis of [MnF6]2− complexes and affecting the optical absorption of the phosphors. Strategies are discussed to identify impurities and to achieve pure and stable phosphors with internal quantum efficiencies of more than 90%. |
| Databáze: | OpenAIRE |
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