As an Hg-free lamp using phosphor, the Bi3+ and Eu3+ co-doped Y2O2S phosphors were prepared and their luminescence properties under vacuum ultraviolet(VUV) excitation were investigated. The VUV photoluminescent intensity of Y2O2S:Eu3+ was weak, however, considerably stronger red emission at 626 nm with good color purity was observed in Y2O2S:Eu3+,Bi3+ systems. Investigation on the photoluminescence reveals that the strong VUV luminescence of Y2O2S:Eu3+,Bi3+ at 147 nm is mainly because the Bi3+ acts as a medium and effectively performs the energy transfer process: Y3+-O2-→Bi3+→Eu3+, while the intense emission band at 172 nm is attributed to the absorption of the characteristic 1S0-1P1 transition of Bi3+ and the direct energy transfer from Bi3+ to Eu3+. The Y2O2S:Eu3+,Bi3+ shows excellent VUV optical properties compared with the commercial (Y,Gd)BO3:Eu3+. Thus, the Y2O2S:Eu3+,Bi3+ can be a potential red VUV-excited candidate applied in Hg-free lamps for backlight of liquid crystal display. As a Hg-free lamp using phosphor, the Bi3 + and Eu3 + co-doped Y2O2S phosphors were prepared and their luminescence properties under vacuum ultraviolet (VUV) excitation were investigated. The VUV photoluminescent intensity of Y2O2S: Eu3 + was weak, however, strongly stronger emission at 626 nm with good color purity was observed in Y2O2S: Eu3 +, Bi3 + systems. Investigation on the photoluminescence reveals that the strong VUV luminescence of Y2O2S: Eu3 +, Bi3 + at 147 nm is mainly because the Bi3 + acts as a medium and effectively performs the energy transfer process: Y3 + -O2- → Bi3 + → Eu3 +, while the intense emission band at 172 nm is attributed to the absorption of the characteristic 1S0-1P1 transition of Bi3 + and the direct energy transfer from Bi3 + to Eu3 +. The Y2O2S: Eu3 + Bi3 + shows excellent VUV optical properties compared with the commercial (Y, Gd) BO3: Eu3 +. Thus, the Y2O2S: Eu3 +, Bi3 + can be a potential red VUV-excited candidate applied in Hg-free lamps for backlight of liquid crystal di splay.