Realization of a green-emitting pyrosilicate-structured Er3+-activated Y2Si2O7 phosphor: a systematic study of opto-electronic characteristics and thermal stability for lighting applications

Abstract

A series of green-emitting Y_2−xSi₂O₇:xEr³⁺ phosphors (x = 1–7 mol%) have been successfully synthesized using a straightforward gel-combustion method facilitated by urea. X-ray diffraction analysis provided specific patterns for samples, confirming a consistent triclinic phase across erbium-doped structures compared to undoped structures. Studies using TEM and EDX were conducted to identify the surface-related characteristics and chemical composition of the synthesized nanophosphor, respectively. The band gap was determined to be 5.55 eV and 5.80 eV for the host material and optimal sample, respectively. The primary peak of excitation, observed at 379 nm, represents the highly sensitive electric dipole transition from the ⁴I_15/2 state to the ⁴G_11/2 level, suggesting that the prepared phosphors could effectively absorb NUV light for activation. The PL profiles of Y_2−xSi₂O₇:xEr³⁺ (x = 1–7 mol%) phosphors demonstrate characteristic emissions at 409 nm (²H_9/2 → ⁴I_15/2), 522 nm (²H_11/2 → ⁴I_15/2), 553 nm (⁴S_3/2 → ⁴I_15/2) and 662 nm (⁴F_9/2 → ⁴I_15/2). In accordance with Dexter's theory, luminescence quenching observed at a concentration of 4 mol% Er³⁺ is attributed to dipole-quadrupole interactions. The optimal sample demonstrates excellent thermal stability, indicated by its luminescence at different temperatures and activation energy of 0.2641 eV. Additionally, the CIE, color purity and CCT values of the fabricated nanomaterials make it ideal for use in lighting applications.