Synthesis of narrow-band red-emitting K2SiF6:Mn4+ phosphors for a deep red monochromatic LED and ultrahigh color quality warm-white LEDs†
In this study, we synthesized and characterized narrow-band red-emitting K2SiF6:Mn4+ phosphors in order to improve the color qualities of warm white light-emitting diodes (LEDs). The deep red monochromatic LED was realized by fabricating a long wavelength pass dichroic filter (LPDF)-capped phosphor-converted LED (pc-LED) with a synthesized K2SiF6:Mn4+ phosphor. In addition, we introduced four-package white LEDs that combine InGaN blue (B) LED and LPDF-capped green (G), amber (A), and red (R) pc-LEDs to achieve the high color rendition at the warm white correlated color temperatures (CCTs, 2700 K) with the assistance of the narrow-band K2SiF6:Mn4+ red phosphor. We compared the optical properties, including the luminous efficacy (LE), luminous efficacy of radiation (LER), color rendering index (CRI), special CRI for strong red (R9), and color quality scale (CQS), of four-package white LEDs by varying the red pc-LED with one narrow-band red-emitting phosphor and five wide-band red-emitting phosphors. The RAGB four-package white LED using narrow-band red-emitting K2SiF6:Mn4+ phosphor exhibited high LE (107 lm W−1) and ultrahigh color qualities (CRI = 94, R9 = 93, and CQS = 93) at a CCT of 2700 K.
- This article is part of the themed collection: JMC C Top Picks collection: Recent progress in light emitting diodes