LED enterprises to improve the white light in the red light emission material
The US Department of Energy has recently set the market standard for lighting-grade white LED luminous efficiency of 200 Im/W. in 2020. Such high efficiency typically requires pc-LEDs to be completed in harsh conditions such as rapid surface photon temperatures up to 200 ° C (generated by high current density) and rapid photon pump rates for the main blue LEDs. Thus, when the fluorescence needs to exhibit high conversion efficiency, rapid attenuation, and high thermal degradation under these conditions.
Recent studies have obtained a new class of nitride materials with very narrow red light emission. Further improvements are expected to be achieved by moving the red light emission spectrum to a shorter wavelength (~ 600-630 nm), preferably with a narrower emission band.
GE (Trigainphosphors) recently commercialized Mn4 + doped fluoride is another type of narrow red light emitting material. There are several sharp lines (about 5 nm) in the vicinity of 630 nm in the emission pattern of these materials, and are highly CRI and high luminous efficiency lamps when combined with green-yellow luminescent garnet materials. However, the longer luminescence decay time of Mn4 + and the lower thermal stability of the ion fluoride donor material are likely to limit the practical application of these phosphors to relatively low current density and low heat generation products.
Finally, hybrid devices with direct red-emitting LEDs combined with complementary pc-LEDs can also be used as high-quality lighting. However, the direct sensitivity of the red LED requires a more complex structural design and limits its application to low thermal confinement areas such as non-directional large area lighting.