Preparation And Properties Of Carbazole-Containing Room-Temperature Phosphorescent Materials

Long-life organic room-temperature phosphorescent materials have attracted widespread attention at home and abroad in recent years due to their low cost,good biocompatibility and ease of modification.They have broad application prospects in chemical sensing,biological imaging,data encryption,information security,etc.Because solid substrates can provide a good rigid environment and effectively inhibit non-radiative leap process,materials have good room-temperature phosphorescent emission properties.Polymer-based room-temperature phosphorescent materials can not only achieve long-life phosphorescent emission,but also have good flexibility,film-forming properties,transparency and other characteristics.Therefore,it is of great significance to explore long-lived solid-based room temperature phosphorescent materials.In this paper,starting from the perspectives of synthesizing new organic phosphorescent small molecules and preparing new solid substrates,room-temperature phosphorescent materials were effectively prepared by adsorbing indolo[3,2-b]carbazole derivatives into filter paper-based materials and doping carbazole boronic acid derivatives into polyvinyl alcohol（PVA）substrates.The photophysical properties of these materials were investigated to explore their luminescent mechanism and functionality,respectively.The specific research content include the following two parts:（1）Three indolo[3,2-b]carbazole derivatives（ICz S2Br,ICz S3Br,ICz S4Br）were designed and synthesized,and they were combined with filter paper substrates pretreated with tert-butanol potassium（t-Bu OK）,respectively,to achieve long-lived room temperature phosphorescence emission.Compared with ICz S3Br and ICz S4Br,the filter paper sample adsorbed with ICz S2Br has better phosphorescence properties,with a phosphorescence lifetime of up to 1070 ms and an afterglow duration of up to 5s.The rigid environment constructed by hydrogen bond in cellulose effectively inhibits non radiative transitions of molecules;in addition,the heavy atom effect of the intramolecular bromine atom promoted the intersystem crossing（ISC）process of excitons from the singlet state to the triplet excited state,and the two reasons together led to the room-temperature phosphorescence（RTP）emission of ICz S2Br molecule.Accordingly,we propose a mechanism for the RTP emission from the adsorption of ICz S2Br molecules on filter paper.In addition,ICz S2Br filter paper samples exhibited reversible RTP emission stimulation response phenomenon during heating/water fumigation treatment,which can be used to design humidity sensing materials.（2）Three carbazole boronic acid derivatives were designed and synthesized,and seven carbazole boronic acid derivatives were doped into PVA substrates to prepare long-lived flexible room-temperature phosphorescent films.Among them,the Cz BOH₁@PVA films emitted phosphorescent lifetime of up to 3640 ms at room temperature,and a long blue afterglow emission of over 20 s could be observed after irradiation with a 275 nm ultraviolet lamp.This is because the PVA diol structure can interact with the phosphor molecule by hydrogen bonding,which together build a rigid environment,effectively inhibits the non radiative transition of the phosphor molecule and the burst of the triplet state exciton,thus achieving long-lived phosphorescence emission.In addition,this thesis investigates the application of carbazole boronic acid derivatives@PVA films in humidity sensing materials.