This disclosure relates to use of group 4 element codoping in a phosphor layer of activator-doped zinc sulfide of a display element, a display element, and a method for manufacturing a display element. The display element (100) comprises a first insulator layer (111), a second insulator layer (112), and a first phosphor layer (121) of activator-group 4 element codoped zinc sulfide between the first insulator layer (111) and the second insulator layer (112). The first phosphor layer (121) has an average atomic percentage of group 4 elements of at least 0.01 atomic percent.

Disclosed is a quantum dot light emitting device including a ligand-substituted quantum dot light emitting layer with a polymer having amine groups. The introduction of the ligand-substituted quantum dot light emitting layer with a polymer having amine groups changes the energy level of an electron transport layer and enables control over the charge injection properties of the device so that the flow of electrons can be controlled. In addition, the ligand substitution is effective in removing oleic acid as a stabilizer of quantum dots to prevent an increase in driving voltage caused by the introduction of the additional material, achieving markedly improved efficiency of the device. Also disclosed is a method for fabricating the quantum dot light emitting device.

Emissive layers for electroluminescent display devices are described herein. The emissive layer can include a two-dopant system having a population of quantum dots (QDs) and a population of molecules exhibiting thermally activated delayed fluorescence (TADF). In some instances, one or both of the QDs and TADF molecules can be disposed in a host matrix. In some instances, the QDs and TADF molecules can be disposed in separate host matrices. In some instances, an electroluminescent display device can include an emissive layer comprising a population of quantum dots (QDs) and a layer adjacent to the emissive layer, the adjacent layer comprising a population of molecules exhibiting thermally activated delayed fluorescence (TADF).

Disclosed is a quantum dot light emitting device including a ligand-substituted quantum dot light emitting layer with a polymer having amine groups. The introduction of the ligand-substituted quantum dot light emitting layer with a polymer having amine groups changes the energy level of an electron transport layer and enables control over the charge injection properties of the device so that the flow of electrons can be controlled. In addition, the ligand substitution is effective in removing oleic acid as a stabilizer of quantum dots to prevent an increase in driving voltage caused by the introduction of the additional material, achieving markedly improved efficiency of the device. Also disclosed is a method for fabricating the quantum dot light emitting device.