Highly Efficient Red/Orange-red Emitting Eu3+ and Sm3+/Eu3+ Co-doped Phosphors with their Versatile Applications

Abstract

In the present work, a series of narrowband red-emitting Li2La4(MoO4)7:Eu3+ (LLM:Eu) phosphors were synthesized through a high-temperature conventional solid-state approach. All the synthesized phosphors crystalized in a tetragonal structure with I41/a space group. Either 395 nm near-UV light or 465 nm blue light can efficiently excite these synthesized phosphors, producing red light with a prominent wavelength of 616 nm. The optimum product of high-concentration quenching was Li2La4(MoO4)7:1.8Eu3+, which reached a high color purity (CP) of 97.28% with a greater internal quantum efficiency (IQE) of 89.6%. The Eu3+ emission from the Li2La4(MoO4)7:1.8Eu3+ phosphor presents excellent thermal stability (81.75% at 423K) demonstrated by temperature-dependent photoluminescence spectra. Solid solution phosphors were synthesized to enhance the photophysical properties in line with the above. The IQE and thermal stability were increased to 92.54% and 86.12%, respectively. When mixed with yellow organic dye and blue LED chip, our red component boosts the CRI and CCT of the customizable white light emitting diodes (WLEDs). The WLED produced by Li2La4(MoO4)7:1.8Eu3+ red phosphor exhibited superior white light emission with a good CRI (83) and CCT value (4925 K), which further enhanced (CRI = 86 and CCT = 5371 K) in the case of Li2La2.2Eu1.8(MoO4)4(WO4)3 solid solution phosphor. Prospective uses of the phosphors that are now being synthesized include security applications (to identify latent fingerprints and in the anti-counterfeit field). Additionally, Eu3+/Sm3+ co-doped red/deep red-emitting phosphors were synthesized and studied their photophysical properties in detail to use for the fabrication of red/deep red LEDs as a light source to promote plant development.