Stabilization,Assembly,and Photoelectrical Properties of Metal Chalcogenide Nanocluster-Based Semiconductor

Author:Lin Jian

Supervisor:wu tao


Degree Year:2017





Semiconductor material is the backbone of information society,which is used to construct various electronic parts and components based on their tunable conductivity.Bringing nanotechnology into traditional semiconductors further expanded their application scope.Investigation on the structure-property relationship of these nano-materials mainly based on the crystalline phase characterization,TEM morphology and structure analysis.However,the above techniques have limitations,for example aberration-corrected scanning TEM is performed under high vacuum,which has many limitations in characterizing testing samples.Herein,central problem is how to realize the investigation of structure-property relationship by a simple way.The emergence of single crystal X-ray diffraction(SCXRD)technique provides a more direct method to study the fine structure-property relationships in crystalline materials.Although SCXRD is not suit for the nano-materials,nanoclusters(NCs)with similar structural characteristic are widely characterized by SCXRD due to their ability to assemble into single crystals.For example,abundant noble metal NCs with precise structure has been applied to investigate the close relationship with their catalytic properties through SCXRD technique.Besides,traditional metal chalcogenide semiconductors with tunable structure and composition could also assemble into single-crystal structure through specific metal chalcogenide NCs.Hitherto,investigation on the crystalline metal chalcogenides(CMCs)that based on NCs is mainly concentrated in creating structural diversity in synthetic view.The unique potential performance of these size-uniform NC that stabilized by crystallization through in-situ self-assemble process is always neglected by researchers.Such as exploration of semiconductor-related photoelectric properties and fine structure-property relationship base on structurally well-known NC-based metal chalcogenides.Therefore,we made great research efforts on developing new properties of structurally well-known NC-based CMCs and their chemical modification method.In addition,NC-based CMCs were also served as a structural platform to investigate the fine structure-property relationship on their photoelectric properties and regulation method.Main results are shown as follows.Chapter 1.Starting from traditional metal chalcogenides,we brought out the structural characteristic and stabilization method of NC-based CMCs.By reviewing references,we summarized the status quo of performance development of CMCs and current understanding on the investigation of fine structure-property relationship through NC-based CMCs.Chapter 2.Based on the Mn2+ doped ISC-10-CdInS(Mn@Cd6In28S56,Mn@CdInS),we extend the potential applications of Mn@CdInS in photoluminescence(PL)and Electrochemiluminescence(ECL).Through in-situ doping Mn2+ into the ISC-10-CdInS,we greatly improved the quantum efficiency of Mn@CdInS(0.53%→ 43.68%).Mn@MnInS(Mn@Mn6In28S56)produced from overwhelming doping of Mn2+ exhibits completely different PL properties.The results proved that the doping site of Mn2+ could be precisely regulated through controlling the doping level of Mn2+.ECL investigation on the ISC-10-CdInS and Mn@CdInS indicated that they possess tunable ECL characteristic.A primary mechanism that how metal vacancy in ISC-10-CdInS participates in the oxidation coreaction was proposed according to the ECL signals from different coreactantChapter 3.A series of Mn2+ doped NCs prepared from in-situ Mn2+ doping strategy were performed as a structural platform to investigate the Mn2+-related PL regulation behaviors by precisely Mn2+ doped structures.The typical PL emission and lifetime of Mn2+ were gradually shift from 615 to 643 nm and 40 μs to 1 ms respectively in these NCs with similar structure and size but different compositions.In addition,regulation on the aggregation state of Mn2+ in these NCs could successfully alter the Mn2+ related forbidden transition and their related PL excitation mechanism.While the aggregation number of Mn2+ in the NC is less than 4,the emission of Mn2+ are largely realized through energy transfer.While the aggregation number of Mn2+ in the NC is equal or greater than 4,the emission of Mn2+ could be achieved through direct excitation.Combining with the analysis results of pressure and low temperature dependent PL spectra as well as Mn2+ doped NC structures,we experimentally confirmed that the regulation on the red emission of Mn2+ could be achieved by adjusting the surrounding lattice stress on Mn2.Chapter 4.An interrupted chalcogenide-based semiconductor zeolite-analog[In28Se54(H2O)4]24-·24(H+-PR)·n(H2O)(CSZ-5-InSe;PR:piperidine)were used to investigate the relation of unique In3+ sites in the interrupted structure and oxygen reduction reaction(ORR)properties and their catalytic mechanism.Specific In3+ sites replaced by in-situ doped Bi3+ revealed that inactive In3+ could exhibit catalytic activity under special structure formation.Based on the structural model of CSZ-5-InSe,we studied the alloying properties of NCs while they were embedded in the covalent superlattice.Sulfurated CSZ-5-InSe showed limited sulfur-alloying level(<20 at%)but large band gap changes(~1.0 eV).Chapter 5.We also investigated the structure regulation factors in the solvothermal synthesis of CMCs.Through altering the reaction temperature and precursor feed ratios of elemental In and Se,structurally unstable phase CSZ-5-InSe was transferred to a non-interrupted 2D In-Se layer.Slightly alter the template that used to prepare CSZ-5-InSe,a novel 3D In-Se framework that build from the non-zinc blende-type fragment was obtained.Chapter 6.We investigated the self-assemble structure characteristic of metal chalcogenide NC(Ge4S10)hybridizes with viologen derivatives.Viologen with benzyl group generated a balance of photoelectric-sensitivity and photostability in the ion-pair hybrids.