Disclosed is an organic electroluminescent device, wherein the light-emitting layer is composed of a non-doped neutral free-radical electroluminescent material or a neutral free-radical electroluminescent material doped in a matrix material. The luminescence of the device is from the photons emitted from the transition of doublet electrons in the outer molecular orbit of the neutral free-radical electroluminescent material from an excited state to the ground state; since there is no limitation on spin-forbidden, the upper limit of the internal quantum efficiency of the device is 100%. The neutral free-radical electroluminescent material used in the device is 1,3-bis(diphenylene)-2-phenylallyl free radicals and derivatives thereof; tri(2,4,6-trichlorophenyl)methyl free radicals and derivatives thereof; (3,5-dichloro-4-pyridyl)bis(2,4,6-trichlorophenyl)methyl free radicals and derivatives thereof; (2,4,6-trichloro-5-pyrimidinyl)bis(2,4,6-trichlorophenyl)methyl free radicals and derivatives thereof.