Luminescence properties and energy transfer mechanism of La2ZnTiO6:Mn4+/Er3+ far-red/green dual-emitting phosphors for plant lighting

A new far-red/green dual-emitting phosphor La 2 ZnTiO 6 :Mn 4+ /Er 3+ (LZT:Mn 4+ /Er 3+ ) was successfully synthesized by the sol-gel method. Under 381 ​nm excitation, LZT:Mn 4+ /Er 3+ phosphor shows the strong far-red emission peak of 709 ​nm (Mn 4+ : 2 E g → 4 A 2g ) and weak green emission peak of 523/548 ​nm (Er 3+ : 2 H 11/2 / 4 S 3/2  ​→ ​ 4 I 15/2 ), which consistent with the requirement of plant growth for far-red and green light. A 1.5-fold enhancement of far-red emission intensity is found in LZT:Mn 4+ /Er 3+ phosphor compared with the Mn 4+ singly-doped counterparts. Moreover, the relative emission intensity of far-red and green can be easily controlled by changing temperature. Utilizing the optimal LZT:0.2%Mn 4+ /2%Er 3+ phosphor as plant lighting, a prototype near-UV-pumped LED device was fabricated. Upon 120 ​mA driving current, it demonstrated far-red/green dual emission. All the results indicated that the LZT:Mn 4+ /Er 3+ phosphor is a potential material for plant growth illumination with far-red/green light.