A novel red-emitting K5La(MoO4)4:Eu3+phosphor with a high quantum efficiency for w-LEDs and visualization of latent fingerprints

A new series of red luminescent K5La(MoO4)4:xEu3+ (KLMO:xEu3+) phosphors (x = 0.05-1.00 mol) was successfully synthesized by a high-temperature solid phase reaction at a low reaction temperature (600 celcius). The X-ray diffraction (XRD) pattern, photoluminescence properties, thermal quenching mechanism, quantum efficiency, and lifetime decay curves of the phosphors were measured and discussed in detail. The prepared phosphors exhibited strong red-light emission (at 615 nm) upon excitation at 394 nm, attributed to the electric dipole 5D0-7F2 transition of Eu3+. The optimal doping concentration of phosphors is 0.8 mol. The quenching temperature of the KLMO:0.80Eu3+ phosphor was found to exceed 480 K, with high activation energy (Ea) of 0.43 eV, showing good thermal stability. Impressively, the KLMO:0.80Eu3+ phosphor with a 0.8 mol concentration of Eu3+ doping also has an internal quantum efficiency (IQE) of up to 84.5%. The packaged white light emitting diode (w-LED) showed a good color rendering index (CRI) (89), correlated color temperature (CCT) (5117 K), and the Commission International de L ' Eclairage (CIE) chromaticity coordinates (0.342, 0.345). Furthermore, the KLMO:0.80Eu3+ phosphor was surface-functionalized with oleic acid (OA) (KLMO:0.80Eu3+@OA) to help better identify Level I-III fingerprint details with high resolution and contrast. The results show that the KLMO:Eu3+ and KLMO:Eu3+@OA phosphors have very promising applications in the w-LEDs and latent fingerprints (LFPs). (c) 2023 Elsevier B.V. All rights reserved.

Automated summary

A new series of red luminescent K5La(MoO4)4:xEu3+ (KLMO:xEu3+) phosphors were synthesized successfully through a high-temperature solid phase reaction at a low reaction temperature (600°C). The XRD pattern, photoluminescence properties, thermal quenching mechanism, quantum efficiency, and lifetime decay curves of the phosphors were measured and discussed in detail. The optimal doping concentration of phosphors is 0.8 mol. The prepared phosphors exhibited strong red-light emission (at 615 nm) upon excitation at 394 nm, attributed to the electric dipole 5D0-7F2 transition of Eu3+. The KLMO:0.80Eu3+ phosphor showed good thermal stability with a quenching temperature exceeding 480 K and a high activation energy of 0.43 eV. Impressively, the KLMO:0.80Eu3+ phosphor also demonstrated a high internal quantum efficiency (IQE) of up to 84.5%. The packaged white light emitting diode (w-LED) using KLMO:0.80Eu3+ phosphor exhibited a good color rendering index (CRI) (89), correlated color temperature (CCT) (5117 K), and Commission International de L'Eclairage (CIE) chromaticity coordinates (0.342, 0.345). Furthermore, surface-functionalization of KLMO:0.80Eu3+ phosphor with oleic acid (OA) (KLMO:0.80Eu3+@OA) showed potential in identifying Level I-III fingerprint details with high resolution and contrast. The results suggest promising applications of KLMO:Eu3+ and KLMO:Eu3+@OA phosphors in w-LEDs and latent fingerprints (LFPs).