Design,Synthesis And Application Of Singlecomponent Circular Polarized Organic Room Temperature Phosphorescent Materials Based On Indolocarbazole Derivatives

Circularly polarized luminescence（CPL）materials with efficient emission have attracted extensive attention for their potential applications in various optoelectronic fields.Generally,CPL-active materials are mainly composed of two parts,namely luminophores and chiral environment.In recent years,luminophores including diverse organic molecules and inorganic nanoparticles were selected to produce CPL-active materials with tunable wavelengths and controlled photophysical properties.On the other hand,diverse strategies were developed to build a chiral environment to control the CPL direction and to achieve stronger CPL strength with higher dissymmetric factors(g_lum).However,the research on CPL mainly focuses on the singlet excited state,and the circularly polarized room temperature phosphorescence（CPRTP）materials based on triplet excitons are rarely reported due to the spin-forbidden barrier.Circularly polarized organic room temperature phosphorescent materials have become a research hotspot recently due to the combination of CPL and RTP properties.Considering the inherent difficulties in promoting the intersystem crossing and aggregation coupling of RTP in pure organic molecules and achieving efficient transfer of chiral groups of CPL to luminescent aggregates,realization of CPL in metal-free room temperature phosphorescent materials remains a challenge.Previous studies have mainly focused on multicomponent host-guest systems.Based on this,the development of single-component circularly polarized organic room temperature phosphorescent materials is of key significance.Aiming at the existing problems of CPRTP,this thesis designed and synthesized two single-component circularly polarized organic room temperature phosphorescent materials through two strategies and realized the dual characteristics of CPL and RTP.Furthermore,their application in the field of information encryption has been investigated.The specific contents are as follows:1.Research on the Circularly Polarized Luminescence Properties Induced by Chiral Room Temperature Phosphorescent MoleculesIn this work,one purely organic molecule with CPRTP luminescence properties was successfully designed and constructed by adding chiral groups to the phosphorescent chromophore,and the g_lumreached a maximum of|5.0×10^-3|.Chiral groups can not only serve as chiral units to realize CPL,but also act as conformational regulators to efficiently manipulate molecular packing patterns.In Ben-2S,a highly twisted donor-acceptor structure facilitates the formation of a smallΔE_STbetween the high-energy singlet and triplet excited states,facilitating the ISC process.The C-H···πinteraction in T-dimer shortens the distance between indolyl and phenyl groups in adjacent molecules and promotes intermolecular charge transfer.Furthermore,T-type interactions stabilize triplet excited states by confining free rotational motion and suppressing molecular thermal vibrations.This work will provide new ideas for the enhancement of ISC and the suppression of the nonradiative deactivation process,and provide new insights for the design of other novel and efficient chiral organic room temperature phosphorescent materials2.Research on the Circularly Polarized Luminescence Properties Induced by Self-assembly of Mesomeric Room-Temperature Phosphorescent MoleculesIn view of the problems of high cost of chiral raw materials and cumbersome synthesis steps,we propose a new strategy to realize chiral room temperature phosphorescence,that is,meso-phosphorescent molecules induce circularly polarized luminescence through self-assembly,while the whole system still maintains good room temperature phosphorescence properties.By introducing octadecyl and halide ions through N-alkylation,two room-temperature phosphorescent materials with different afterglow colors and an afterglow lifetime longer than 200 ms were synthesized.Notably,Br-Ben-C18 showed white room-temperature phosphorescence at room temperature,which provides a new idea for designing single-component white room-temperature phosphorescent materials.In addition,the meso-space structure enables the introduced alkyl chains to form a directional arrangement in space under the electrostatic induction of the benzene rings at both ends.Due to the strong intramolecular/intermolecular interactions,helical nanofibers are spontaneously formed with the generation of a single CPL signal.Finally,it shows tunable afterglow color for the variably dual emission of TADF and RTP in Ben-C18 and Br-Ben-C18 molecules at different temperatures.Thus,they can be applied in the anti-counterfeiting and information encryption field.