Fabrication,luminescent Properties And Electroluminescent Devices Of Quantum Dots Based On G-C₃N₄ Structure Modification

Quantum dot light-emitting diode(QLED)electroluminescent devices have been applied in the fields of transparent display and flexible display.The technical characteristics of QLED to directly convert electric energy into light energy provide a new technical means for obtaining effective light emission.In the future,it has a broad development prospect in ultraviolet sterilization,industrial curing and other fields.In order to overcome the problems of heavy metal pollution and toxicity in the existing quantum dot materials,g-C₃N₄ was used as the main material in this paper,and two different kinds of ultraviolet quantum dots were obtained by structural modification.Furthermore,the fluorescence mechanism of quantum dots and its application in display devices were further studied.The content and results of the paper are as follows:(1)Using bulk g-C₃N₄ solid powder as raw material,the ultraviolet luminescent quantum dots(QDs)with the peak emission wavelength at 365 nm were successfully prepared through the reaction route of intercalation and reverse pyrolysis.The ultraviolet luminescence comes from the synergistic effect of the g-C₃N₄ base substructure,the large?bond is dissociated,and the electrons return to the ground state from the?*anti-bonding orbital to the unbonded lone pair electron state,and the LP-?*electron transition radiation presents ultraviolet light.QLED with a peak emission wavelength of 399 nm were successfully fabricated by using ultraviolet quantum dots prepared directly in DMF solution by ultrasonic and hydrothermal method.(2)We selected different boron sources to modify the structure of g-C₃N₄ with melamine as the precursor.Among these,we find the effect of C₆H₁₈BN doping is the best.Further,the C₆H₁₈BN doping process is optimized.The stepwise firing process of low temperature and then high temperature has a deeper reaction degree.In the process of doping with C₆H₁₈BN,a small amount of doping can enhance the rigidity of the sample structure and greatly increase the fluorescence intensity.The doping degree is further improved,and the electron transitions in different energy levels to obtain different luminescence.The sample presents high quality white light(color rendering index up to 93.69%).However,luminescence intensity quenches seriously owing to multiple reasons including the destruction of the rigid structure,the further doping of B atom,the introduction of more impurity energy levels,and orderly arranged cracking in the plane of the sample.The proportion of small molecules doped in the corresponding quantum dot solution is larger than that in the powder sample,and it exhibits stronger fluorescence efficiency,which dominates the luminescence.The main emission peak is about 365 nm,which can be uniformly dispersed in the organic solution to be applied to QLED devices.