Photoluminescence and thermal stability of Mn²⁺ co-doped SrSi₂O₂N₂:Eu²⁺green phosphor synthesized by sol-gel method

Eu²⁺ and Mn²⁺ co-doped SrSi₂O ₂N₂ phosphors were firstly synthesized via a simple sol-gel method using low-cost SrCO₃, Eu₂O₃, Mn(CH₃COO)₂ × 4H₂O, α-Si ₃N₄ and C₈H₂₀O₄Si (TEOS) as the starting materials. Their luminescence properties, quantum yield, and thermal stability were investigated in comparison with the single Eu ²⁺ doped samples. The green emission intensity of Eu²⁺ ions is greatly enhanced by introducing Mn²⁺ ions into SrSi ₂O₂N₂:Eu²⁺ due to the coexcitation and energy transfer between Mn²⁺ and Eu²⁺. The energy transfer probability from Mn²⁺ to Eu²⁺ depends strongly on the Mn²⁺ concentration, which is maximized at 2.0 mol%. Mn ²⁺. Simultaneously, quantum efficiency and thermal stability in SrSi₂O₂N₂:0.03Eu²⁺, 0.02Mn ²⁺ is dramatically improved. All these excellent optical properties indicate that SrSi₂O₂N₂:Eu²⁺, Mn²⁺ synthesized in the present work is a promising green-emitting phosphor for white-light emitting diodes with near-UV LED chips.