Near-infrared emission of Yb3+ sensitized by Mn4+ in La2MgTiO6

Mn4+/Yb3+ co-doped La2MgTiO6 near infrared phosphor were prepared by co-precipitation technique. The La2MgTiO6: Mn4+, Yb3+ phosphors can convert the short-wavelength sunlight in 250-550 nm spectral region into near infrared emission at 990 nm, which matches well with the high photosensitive region of Si-based solar cells. The mechanisms for the Mn4+ -> Yb3+ have been discussed based on the Mn4+ and Yb3+ concentration dependent steady-state and transient luminescence properties. The energy transfer efficiency is 31% in the La1.91MgTi0.998O6: 0.002Mn, 0.09Yb sample with the maximal 990 nm emission intensity. It is found that phonon-assisted energy transfer plays an important role in sensitization process from Mn4+ to Yb3+ in the Mn4+/Yb3+ co-doped La2MgTiO6.