FigsharePub Date : 2018-05-04DOI: 10.1021/acs.jpcc.8b02776.s001
David Morgan (479503), David F. Kelley (1358034)
{"title":"Role of Surface States in Silver-Doped CdSe and CdSe/CdSnQuantum Dots","authors":"David Morgan (479503), David F. Kelley (1358034)","doi":"10.1021/acs.jpcc.8b02776.s001","DOIUrl":"https://doi.org/10.1021/acs.jpcc.8b02776.s001","url":null,"abstract":"Theneffects of Ag doping of CdSe and CdSe/CdS quantum dotsn(QDs) have been studied as a function of the surface composition.nThroughout these studies, static and time-resolved luminescence andntransient absorption measurements are used to determine the naturenand rates of radiationless decay mechanisms and how these vary withnthe concentration of Ag dopants. In tributylphosphine-ligated CdSe,nthe photoluminescence quantum yield (PL QY) varies nonmonotonicallynwith dopant concentration, increasing at low concentrations of Ag<sup>+</sup> then decreasing with further addition. The initial increasenis assigned to the passivation of preexisting surface hole traps byninteraction of interstitial Ag<sup>+</sup> with surface Se<sup>2–</sup> ions, whereas the subsequent decrease is due to the introductionnof substitutional Ag<sup>+</sup> dopants, which act as a newnsource of hole traps. Ligation of the particle surface with alkylnamines largely passivates the surface hole traps and thereby eliminatesnthe initial increase in PL QY upon doping. CdSe/CdS QDs ligated withnoleylamine (and no phosphines) exhibit extensive thermal populationnof empty surface orbitals by valence band electrons. Photoexcitationnof these surface-charged particles results in what is essentiallyna positive trion, which can undergo rapid Auger decay. The presencenof oleylamine reduces much of the Ag<sup>+</sup> to Ag<sup>0</sup>, and the addition of Ag<sup>0</sup> dopants passivates these emptynsurface states and eliminates the surface charging and hence positiventrion formation.","PeriodicalId":522161,"journal":{"name":"Figshare","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147892709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}