On the basis of the possibility that there might exist a mixed composition of the Y(As,Nb,P,V)O4 system of better luminescent performance than the single-compound phosphors at the VUV excitation, a solution combinatorial chemistry synthesis and characterization was employed in the present investigation. Quaternary and ternary combinatorial libraries were designed to implement an efficient screening process. In parallel, the first-principle calculations were also carried out on the basis of the density functional theory to give a reasonable interpretation to the results from the combinatorial chemistry screening process. It was found that a new phosphor, Y0.9(P0.92V0.03Nb0.05)O4:Eu3+, which was obtained through the three-step combinatorial screening, shows promising luminance and CIE color chromaticity that could be comparable to the commercially available red phosphor used for the PDP application. As a result of the luminescent mechanism study in association with the calculated density of states (DOS), the entire energy transfer route under the 147-nm excitation was revealed for the newly found phosphor, Y0.9(P0.92V0.03Nb0.05)O4:Eu3+.