Synthesis And Property Study Of Copper-Based Hybrid Luminescent Semiconductors Materials

In recent years,lead-based hybrid metal halide semiconductor materials have become aresearch hotspot in the field of material science because of their excellent optoelectronic properties.Water stability and lead toxicity are the biggest bottlenecks that hindered the wide application of this type hybrid material,although they have shown excellent photoelectric performance.Contrastively,transition metal copper is low cost,hypotoxicity,and has abundant reserves.It is one of the best substitutes for toxic lead in exploring hypotoxicity metal halide semiconductors.However,current research in this aspect is still in the early stage.In this thesis,cuprous halide was selected as the inorganic component,aromatic heterocycles and derivatives were selected as the organic component.The structure,stability,and coordination site of organic components were modulated through the subtle designed in-situ organic reactions.A series of copper-based hybrid semiconductor materials were finally synthesized by the self-assembly of the organic and the inorganic components at the molecular level.The synthesis strategies and structural regulation rules of the materials were summarized by means of detailed experimental researches and theoretical calculations.The application potentials of the synthesized materials in the aspects of photoconductivity,solid-state lighting and optical detection were explored in detail.The results are as follows:1.Three one-dimensional hybrid semiconductors were synthesized under facile solvothermal synthesis conditions.（Mebti）₂Cu₃I₅（1,Mebti=3-methylbenzo[d]thiazol-3-ium）was prepared by using alkylated benzothiazole as the counter cation,which represents the first example of hybrid semiconductor containing chain-like（Cu₃I₅）^2–.Structurally,（Cu₃I₅）^2–exhibits a rare structure connected by（Cu I₄）tetrahedrons and（Cu I₃）plane triangles.The N atom in benzothiazole was alkylated,which prevent the organic component from forming coordination bond,strong hydrogen bond and halogen bond with inorganic component.Correspondingly,1 exhibits a rare structural feature that the inorganic components combine with the organic component only through Coulomb force.The photoconductive film device of1 fabricated by the recrystallization method exhibits good electrical conductivity and high light response,showing great application potentials in hypotoxic photodetectors.Adjusting the reaction conditions to make the N or S donor atoms in the benzothiazole derivatives forming coordination bonds with the inorganic copper-iodine component,we obtained two one-dimensional hybrid semiconductor materials Cu I（BTZ）（2,BTZ=Benzo（d）thiazole）and Cu I（PBT）（3,PBT=3-Propyl-3H-benzothiazole-2-thione）,Compounds 2 and 3 have similar one-dimensional ladder-like copper-iodine chains but exhibit completely different photoelectric responses because they contain different organic ligands.Detailed structural analysies and density functional theory calculations were employed to disclose the different energy band structures,electron transmission pathes and the photoresponse mechanisms of the two compounds.This research may help a lot for the further design and synthesis of hybrid semiconductors with excellent optoelectronic properties.2.The first tetranuclear hybrid copper（I）iodine cluster Cu₄I₄（ETBT）₄（4,ETBT=2-ethylbenzo[d]thiazole）constructed by four-coordinated copper were synthesized through a functional synergy strategy.Compound 4 can be used as a dual-functional optical sensor to detect o-nitrophenol（o-NP）and tetracycline hydrochloride（TCH）pollutants in water,with a detection limit（LOD）of 2.30 and 4.15μM,respectively.The detection system includes a pellet sensor fabricated by the polycrystalline powder of 4 and a custom-designed luminescence cell.This system has good dual detection capability,excellent sensitivity and recyclability and easy portability,which is suitable for long-time in-field outdoor detection applications.The present work not only developed the first dual-functional solid sensor for optical detection of o-NP and TCH but also demonstrates the promising future of hybrid copper（I）iodine clusters as solid optical sensors in monitoring environmental pollutants in water systems.3.By regulating the size and coordination sites of the organic ligands,three red light-emitting hexanuclear copper（I）nanoclusters were synthesized,namely Cu₆（BTT）₆（5,BTT=benzo[d]thiazole-2-thiolate）,Cu₆（BPT）₆（6,BPT=5-bromopyridine-2-thiolate）and Cu₆（TPT）₆（7,TPT=5-（trifluoromethyl）pyridine-2-thione）,which all show cluster-centered phosphorescence emissions.The emission bands of the copper（I）nanoclusters displayed stepwise blueshifts from near-infrared region to visible red-light region.It is ascribed to the regulation of the Cu×××Cu distances from the modification of the ligand functional groups.Precise structural analysis,steady-state,transient and temperature-dependent photoluminescence tests and density functional theory calculations were used to reveal their optical mechanisms.This study is the first to report the luminescence regulation of hexanuclear copper（I）clusters on the basis of accurate structural design.Importantly,6 and 7meet the requirements of preparing white light-emitting device（WLED）based on commercial460 nm blue LED chip,because they can be effectively excited by blue light.The fabricated WLEDs and flexible light-emitting thin films emit perfect white light and show good durability,implying the application potentials of multinuclear copper（I）nanoclusters in solid-state lighting area.