Study On Carbonized Polymer Dots /liquid Crystal Composites With Circular Polarization Room Temperature Phosphorescent Effect

Room Temperature Phosphorescent（RTP）materials have been widely used in sensing,bio-imaging and information encryption due to their unique advantages of large Stokes shift and long afterglow emission.As a new nano-sized optical functional material,Carbon Dots（CDs）have the advantages of simple preparation,excellent luminous property and good biocompatibility.Circularly Polarized Luminescence（CPL）materials are a recent hot topic of research.Researchers have developed a range of new CPL materials in the fields of chiral liquid crystals（LCs）,organic small molecules and polymers.However,the current research on CPL is mainly focused on circularly polarized fluorescence emission from a single excited state.It is still difficult to combine chiral and phosphorescence to implant CPL in metal-free RTP materials,especially to prepare circularly polarized room temperature phosphorescence（CPRTP）materials with high asymmetry factor(g_lum)and long phosphorescence lifetime at the same time.In this work,a kind of Carbonized Polymer Dots（CPDs）with long phosphorescence lifetime was designed and prepared,and CPRTP emission with ultra-high g_lum values was achieved by laminating CPDs with Cholesteric Liquid Crystal（CLC）polymer films.Details of the study are as follows:1)Preparation and study of long-lifetime phosphorescent CPDsN,P co-doped CPDs（NP-CPDs）were prepared with 3-（2-Aminoethylamino）propyltriethoxysilane and phosphoric acid as raw materials by hydrothermal reaction at 210℃for 12 h.The NP-CPDs emitted bright green RTP after the excitation light was turned off,with a phosphorescent quantum yield of 9.74%,a phosphorescent lifetime of 1.25 s and an afterglow duration of more than 14 s.The potential applications of NP-CPDs in the fields of anti-counterfeiting,information encryption and fingerprint imaging were explored by taking advantage of the excellent phosphorescent performance.2)Study on the CPRTP effect of CPDs/LC composite photonic filmThe CPDs/LC stacked composite photonic film was designed and fabricated.The unpolarized RTP emitted by NP-CPDs was converted into CPRTP with a g_lum value of 1.09 by using the light filtering effect of CLC polymer film,and the visualization of CPRTP was realized for the first time.Furthermore,by controlling the dot coating position of NP-CPDs and the phase state of the LCs polymer film,a composite photonic array film with information encryption properties has been developed,thus expanding the application of CPRTP materials in anti-counterfeiting.In summary,a kind of CPDs with long RTP lifetime has been investigated and prepared in this thesis,and a CPRTP emission with ultra-high g_lum and long phosphorescence lifetime has been achieved by using selective reflection of CLC polymer film.