A quantum dot light-emitting device, comprising: a base substrate (200; 300; 400); and a first electrode layer (201; 301; 401), a light-emitting layer (202; 302; 402), a second electrode layer (203; 303; 403 ) and an encapsulation layer (204; 304; 404) which are sequentially formed on the base substrate (200; 300; 400), wherein the light-emitting layer (202; 302; 402) comprises a quantum dot light emitting material; a fluorescent material is disposed between the first electrode layer (201; 301; P401) and the second electrode layer (203; 303; 403); one of the first electrode layer (201; 301; 401 ) and the second electrode layer (203; 303; 403 ) is an anode layer, and the other of the first electrode layer (201; 301; 401) and the second electrode layer (203; 303; 403) is a cathode layer, wherein the fluorescent material comprises a thermally activated delayed fluorescence material and wherein the thermally activated delayed fluorescence material is a mixture comprising a host material and a guest material; characterized in that : at least a portion of a fluorescence emission spectrum of the thermally activated delayed fluorescence material overlaps an absorption spectrum of the quantum dot light emitting material, and the overlap area accounts for not less than 30% of an area of the fluorescence emission spectrum of the guest material; the fluorescent material forms an energy transfer layer (205; 305, 306; 405, 406) at one side or both sides of the light emitting layer (202; 302; 402), and the energy transfer layer (205; 305, 306; 405, 406) is in contact with the light emitting layer (202; 302; 402). a base substrate (200; 300; 400); and a first electrode layer (201; 301; 401), a light-emitting layer (202; 302; 402), a second electrode layer (203; 303; 403 ) and an encapsulation layer (204; 304; 404) which are sequentially formed on the base substrate (200; 300; 400), wherein the light-emitting layer (202; 302; 402) comprises a quantum dot light emitting material; a fluorescent material is disposed between the first electrode layer (201; 301; P401) and the second electrode layer (203; 303; 403); one of the first electrode layer (201; 301; 401 ) and the second electrode layer (203; 303; 403 ) is an anode layer, and the other of the first electrode layer (201; 301; 401) and the second electrode layer (203; 303; 403) is a cathode layer, wherein the fluorescent material comprises a thermally activated delayed fluorescence material and wherein the thermally activated delayed fluorescence material is a mixture comprising a host material and a guest material; characterized in that : at least a portion of a fluorescence emission spectrum of the thermally activated delayed fluorescence material overlaps an absorption spectrum of the quantum dot light emitting material, and the overlap area accounts for not less than 30% of an area of the fluorescence emission spectrum of the guest material; the fluorescent material forms an energy transfer layer (205; 305, 306; 405, 406) at one side or both sides of the light emitting layer (202; 302; 402), and the energy transfer layer (205; 305, 306; 405, 406) is in contact with the light emitting layer (202; 302; 402). at least a portion of a fluorescence emission spectrum of the thermally activated delayed fluorescence material overlaps an absorption spectrum of the quantum dot light emitting material, and the overlap area accounts for not less than 30% of an area of the fluorescence emission spectrum of the guest material; the fluorescent material forms an energy transfer layer (205; 305, 306; 405, 406) at one side or both sides of the light emitting layer (202; 302; 402), and the energy transfer layer (205; 305, 306; 405, 406) is in contact with the light emitting layer (202; 302; 402). <EOS>