Realization of tunable emission via efficient Tb3+–Eu3+ energy transfer in K3Gd(PO4)2 for UV-excited white light-emitting-diodes

• A novel orange-yellow emitting phosphor: K3Gd(PO4)2:Tb3+, Eu3+ was prepared.
• The energy transfer from Tb3+ to Eu3+ in K3Gd(PO4)2 was investigated carefully.
• K3Gd(PO4)2:Tb3+, Eu3+ can realize tunable color emission from greenish to orange.

A n-UV convertible phosphor K3Gd(PO4)2:Tb3+, Eu3+ with tunable-emitting color has been synthesized by the solid state reaction. Under the Tb3+ excitation (373 nm), the Eu3+ emissions increase dramatically with increasing the Eu3+ content due to the efficient energy transfer from Tb3+ to Eu3+, which has been justified through the luminescence spectra and fluorescence decay curves. K3Gd(PO4)2:0.5Tb3+, yEu3+ can achieve tunable color emissions from yellowish-green through orange-yellow and ultimately to reddish-orange by simply adjusting the Eu3+ content. In addition, the energy transfer mechanism was demonstrated to be the dipole–dipole interaction and the energy transfer efficiency was calculated. The present results indicate that this novel orange-yellow emitting phosphor can be as a potential candidate for the application in white LEDs.