Oxide-Based Red Emitting Phosphors with High Color Purity and Their Versatile Applications: Synthesis, Structure, and Luminescence Properties

The oxide-based narrow band red emitting phosphor is critical and assumes a fundamental part to upgrade the overall efficiency of the white LED. In this regard, a series of Eu3+-activated Na2La4(WO4)7 (NLW) red emitting phosphors were synthesized employing a solid state approach, and we examined their optical properties in detail. All of the compositions crystallize in tetragonal structure with a I41/a space group. Sharp red emission was exhibited by all the NLW:Eu3+ phosphors ∼616 nm owing to the ED transition (5D0 → 7F2), under the excitation of 394 nm and observed concentration quenching when x = 0.8. In addition, color purity and IQE of Na2La3.2(WO4)7:0.8Eu3+ phosphor is found to be 96.79% and 83.76%, respectively. A temperature-dependent PL study reveals the thermal stability of the phosphor as 69.75% at 423 K. Red and white LEDs were fabricated utilizing the synthesized phosphor to understand their practical applicability. EL spectra of the red LED displayed intense red emission, whereas white LED exhibited warm white light with high CRI (80) and low CCT (5730K) values. These Eu3+-doped red phosphors can also be used for latent fingerprint application. Moreover, a series of Sm3+ and simultaneous activation of both Sm3+ and Eu3+ in NLW phosphors were synthesized, and investigated their optical properties. By using the Sm3+-codoped Eu3+-activated phosphor, a red/deep red LED is fabricated for the plant growth purpose. These outcomes suggested that the synthesized phosphors could be promising phosphors for the WLED, security, and plant growth applications.