A polymer material comprising a composition containing a fluorescent conjugated polymer and a phosphorescent compound having a metal complex as a partial structure, and having as a ligand 2-phenylpyridine, 2-phenylquinoline, 1-phenylisoquinoline, 2- or 3-phenylquinoxaline, benzo[h]quinoline, or derivatives thereof, wherein the following conditions, and are satisfied: at least one of the light emission peak wavelengths of the fluorescent conjugated polymer is less than 500 nm, the light emission peak wavelengths of the phosphorescent compound are not less than 500 nm, the following relation is satisfied: ET A − ES A 0 ≥ ET B − ES B 0 − 0.2 unit; eV wherein, ES A0 represents energy of the fluorescent conjugated polymer at the ground state, ET A represents energy of the fluorescent conjugated polymer at the lowest excited triplet state, ES B0 represents energy of the phosphorescent compound at the ground state, and ET B represents energy of the phosphorescent compound at the lowest excited triplet state; wherein ET A, ES A0, ET B and ES B0 are determined using the following method: for the phosphorescent compound, its structure is optimized by density functional theory at B3LYP level, in which 1an12dz is used as a basis function for the center metal contained in the phosphorescent compound and 6-31g* is used as a basis function for other atoms contained in the phosphorescent compound; for the optimized structure, the same basis as for the structure optimization is used, and according to time-dependent density functional (TDDFT) theory at B3LYP level, the difference in energy between the ground state and the lowest excited triplet state, i.e. the lowest excited triplet energy, is calculated; for the fluorescent polymer compound, its structure is optimized using the Hartree Fock method, and the lowest excited triplet energy is measured by time-dependent density functional theory at B3P86 level, in which 6-31g* is used as a basis function; and wherein the proportion of the sum of squares of orbital coefficients of the outermost d orbital of a center metal in the metal complex in the highest occupied molecular orbital (HOMO) calculated by a computational scientific means occupying the sum of squares of orbital coefficients of all orbitals is not less than one-third. at least one of the light emission peak wavelengths of the fluorescent conjugated polymer is less than 500 nm, the light emission peak wavelengths of the phosphorescent compound are not less than 500 nm, the following relation is satisfied: ET A − ES A 0 ≥ ET B − ES B 0 − 0.2 unit; eV wherein, ES A0 represents energy of the fluorescent conjugated polymer at the ground state, ET A represents energy of the fluorescent conjugated polymer at the lowest excited triplet state, ES B0 represents energy of the phosphorescent compound at the ground state, and ET B represents energy of the phosphorescent compound at the lowest excited triplet state; wherein ET A, ES A0, ET B and ES B0 are determined using the following method: for the phosphorescent compound, its structure is optimized by density functional theory at B3LYP level, in which 1an12dz is used as a basis function for the center metal contained in the phosphorescent compound and 6-31g* is used as a basis function for other atoms contained in the phosphorescent compound; for the optimized structure, the same basis as for the structure optimization is used, and according to time-dependent density functional (TDDFT) theory at B3LYP level, the difference in energy between the ground state and the lowest excited triplet state, i.e. the lowest excited triplet energy, is calculated; for the fluorescent polymer compound, its structure is optimized using the Hartree Fock method, and the lowest excited triplet energy is measured by time-dependent density functional theory at B3P86 level, in which 6-31g* is used as a basis function; and wherein the proportion of the sum of squares of orbital coefficients of the outermost d orbital of a center metal in the metal complex in the highest occupied molecular orbital (HOMO) calculated by a computational scientific means occupying the sum of squares of orbital coefficients of all orbitals is not less than one-third. for the phosphorescent compound, its structure is optimized by density functional theory at B3LYP level, in which 1an12dz is used as a basis function for the center metal contained in the phosphorescent compound and 6-31g* is used as a basis function for other atoms contained in the phosphorescent compound; for the optimized structure, the same basis as for the structure optimization is used, and according to time-dependent density functional (TDDFT) theory at B3LYP level, the difference in energy between the ground state and the lowest excited triplet state, i.e. the lowest excited triplet energy, is calculated; for the fluorescent polymer compound, its structure is optimized using the Hartree Fock method, and the lowest excited triplet energy is measured by time-dependent density functional theory at B3P86 level, in which 6-31g* is used as a basis function; and wherein the proportion of the sum of squares of orbital coefficients of the outermost d orbital of a center metal in the metal complex in the highest occupied molecular orbital (HOMO) calculated by a computational scientific means occupying the sum of squares of orbital coefficients of all orbitals is not less than one-third.