Novel EGCG assisted ultrasound synthesis of self-assembled Ca2SiO4:Eu3+ hierarchical superstructures: Photometric characteristics and LED applications

• Ca2SiO4:Eu3+ hierarchical superstructures were synthesized by facile EGCG ultrasound assisted synthesis.
• The particle nucleation and growth of Ca2SiO4:Eu3+ superstructures were analyzed systematically.
• Plausible mechanisms for the morphological evolution of superstructures were proposed.
• The obtained superstructures could be a promising red component for possible applications in white LEDs.

This paper reports for the first time ultrasound, EGCG assisted synthesis of pure and Eu3+ (1–5 mol%) activated Ca2SiO4 nanophosphors having self-assembled superstructures with high purity. The shape, size and morphology of the product were tuned by controlling influential parameters. It was found that morphology was highly dependent on EGCG concentration, sonication time, pH and sonication power. The probable formation mechanism for various hierarchical superstructures was proposed. The PL studies of Ca2SiO4:Eu3+ phosphors can be effectively excited by the near ultraviolet (UV) (396 nm) light and exhibited strong red emission around 613 nm, which was attributed to the Eu3+ (5D0 → 7F2) transition. The concentration quenching phenomenon was explained based on energy transfer between defect and Eu3+ ions, electron–phonon coupling and Eu3+–Eu3+ interaction. The Judd–Ofelt intensity parameters and radiative properties were estimated by using PL emission spectra. The photometric studies indicate that the obtained phosphors could be a promising red component for possible applications in the field of white light emitting diodes.