The Synthesis,mechanism And Applications In White LED Of Full-Color Emissive Carbon Dots

As a new type of carbon-based nanomaterials,carbon quantum dots(CDs)have quantum effects due to their zero-dimensional size.Their unique structure and properties make them one of the most attractive materials in nanoscale.Unlike semiconductor quantum dots,CDs have better biocompatibility due to their carbon-based structure,which is more agree with the needs and development of green chemistry.In addition,CDs are widely used in biomedicine,sensing and detection,optical devices and other fields because of their abundant raw materials,simple and diverse preparation methods,excellent fluorescence performance and strong chemical stability.In this paper,Zn-doped multi-color fluorescent CDs(Zn-CDs)and N-doped multi-color fluorescent CDs(N-CDs)have been prepared by one-step solvothermal method.The synthesis methods,fluorescence properties,morphology and structure of these two kinds of quantum dots are explored and analyzed.The mechanism of fluorescence color change is studied by means of simulation analysis.And their fluorescence wavelength specifications are applied one white light-emitting diodes,of which the basic properties are tested.The main contents are as followed:1.A series of red,purple-red,purple-blue and blue fluorescent CDs are synthesized by controlling the doping amount of Zn source only,with the same precursor and reaction conditions.The fluorescent quantum yield of red Zn-CDs was 5.96%.The prepared carbon dots have uniform size and similar morphology,thus excluding the influence of size effect on fluorescence emission wavelength.Characterization analysis and simulation results show that the fluorescence emission wavelengths of different Zn-CDs are different,which is related to the oxygen content of CDs and the amount of Zn doping.The CDs prepared by this method are used for the preparation of white light emitting diodes and the detection of organic solvents.2.Using p-phenylenediamine as precursor,a series of red,green and blue fluorescent CDs are synthesized by adding modifiers,changing reaction solvent and adjusting reaction time.Among them,the fluorescent quantum yield of red N-CDs is up to 24.7% after optimization.By FTIR,XPS,Raman and other characterization analysis with simulation calculation methods,the emission wavelength of different N-CDs is found most affected by the relative content of different N structures in CDs.The CDs prepared by this method can be applied to the fluorescent materials of white light emitting diodes.