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

Highlights: • A novel far-red/green dual-emitting phosphor was synthesized by sol-gel method. • The relative intensity of far-red/green can be controlled by changing temperature. • The quadrupole-quadrupole interaction was mainly responsible for energy transfer. A new far-red/green dual-emitting phosphor La₂ZnTiO₆:Mn⁴⁺/Er³⁺ (LZT:Mn⁴⁺/Er³⁺) was successfully synthesized by the sol-gel method. Under 381nm excitation, LZT:Mn⁴⁺/Er³⁺ phosphor shows the strong far-red emission peak of 709nm (Mn⁴⁺: ²E_g→⁴A_2g) and weak green emission peak of 523/548nm (Er³⁺: ²H_11/2/⁴S_3/2→⁴I_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:Mn⁴⁺/Er³⁺ phosphor compared with the Mn⁴⁺ 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%Mn⁴⁺/2%Er³⁺ phosphor as plant lighting, a prototype near-UV-pumped LED device was fabricated. Upon 120mA driving current, it demonstrated far-red/green dual emission. All the results indicated that the LZT:Mn⁴⁺/Er³⁺ phosphor is a potential material for plant growth illumination with far-red/green light.