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pH and concentration dependence of the optical properties of thiol-capped CdTe nanocrystals in water and D2O

  • The optical properties of semiconductor nanocrystals (SC NCs) are largely controlled by their size and surface chemistry, i.e., the chemical composition and thickness of inorganic passivation shells and the chemical nature and number of surface ligands as well as the strength of their bonds to surface atoms. The latter is particularly important for CdTe NCs, which – together with alloyed CdₓHg₁₋ₓTe – are the only SC NCs that can be prepared in water in high quality without the need for an additional inorganic passivation shell. Aiming at a better understanding of the role of stabilizing ligands for the control of the application-relevant fluorescence features of SC NCs, we assessed the influence of two of the most commonly used monodentate thiol ligands, thioglycolic acid (TGA) and mercaptopropionic acid (MPA), on the colloidal stability, photoluminescence (PL) quantum yield (QY), and PL decay behavior of a set of CdTe NC colloids. As an indirect measure for the strength of theThe optical properties of semiconductor nanocrystals (SC NCs) are largely controlled by their size and surface chemistry, i.e., the chemical composition and thickness of inorganic passivation shells and the chemical nature and number of surface ligands as well as the strength of their bonds to surface atoms. The latter is particularly important for CdTe NCs, which – together with alloyed CdₓHg₁₋ₓTe – are the only SC NCs that can be prepared in water in high quality without the need for an additional inorganic passivation shell. Aiming at a better understanding of the role of stabilizing ligands for the control of the application-relevant fluorescence features of SC NCs, we assessed the influence of two of the most commonly used monodentate thiol ligands, thioglycolic acid (TGA) and mercaptopropionic acid (MPA), on the colloidal stability, photoluminescence (PL) quantum yield (QY), and PL decay behavior of a set of CdTe NC colloids. As an indirect measure for the strength of the coordinative bond of the ligands to SC NC surface atoms, the influence of the pH (pD) and the concentration on the PL properties of these colloids was examined in water and D₂O and compared to the results from previous dilution studies with a set of thiol-capped Cd₁₋ₓHgₓTe SC NCs in D₂O. As a prerequisite for these studies, the number of surface ligands was determined photometrically at different steps of purification after SC NC synthesis with Ellman’s test. Our results demonstrate ligand control of the pH-dependent PL of these SC NCs, with MPA-stabilized CdTe NCs being less prone to luminescence quenching than TGA-capped ones. For both types of CdTe colloids, ligand desorption is more pronounced in H₂O compared to D₂O, underlining also the role of hydrogen bonding and solvent molecules.zeige mehrzeige weniger
Metadaten
Autoren/innen:Ralf Schneider, Florian Weigert, V. Lesnyak, S. Leubner, T. Lorenz, Thomas Behnke, A. Dubavik, J.-O. Joswig, Ute Resch-Genger, N. Gaponik, A. Eychmüller
Persönliche Herausgeber/innen:Ute Resch-Genger, Ralf Schneider
Dokumenttyp:Zeitschriftenartikel
Veröffentlichungsform:Verlagsliteratur
Sprache:Englisch
Titel des übergeordneten Werkes (Englisch):Physical Chemistry Chemical Physics
Jahr der Erstveröffentlichung:2016
Organisationseinheit der BAM:1 Analytische Chemie; Referenzmaterialien
1 Analytische Chemie; Referenzmaterialien / 1.0 Abteilungsleitung und andere
Veröffentlichende Institution:Bundesanstalt für Materialforschung und -prüfung (BAM)
Herausgeber (Institution):RSC
Verlag:RSC
Verlagsort:Cambridge
Jahrgang/Band:18
Ausgabe/Heft:28
Erste Seite:19083
Letzte Seite:19092
DDC-Klassifikation:Naturwissenschaften und Mathematik / Chemie / Analytische Chemie
Freie Schlagwörter:Fluorescence; Ligand analysis; Nano particles; Quantum dots
Themenfelder/Aktivitätsfelder der BAM:Analytical Sciences
DOI:https://doi.org/10.1039/c6cp03123d
URN:urn:nbn:de:kobv:b43-371253
URL:http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=Alerting&SrcApp=Alerting&DestApp=WOS&DestLinkType=FullRecord;UT=WOS:000379939100046
Verfügbarkeit des Dokuments:Datei für die Öffentlichkeit verfügbar ("Open Access")
Lizenz (Deutsch):License LogoCreative Commons - Namensnennung-Nicht kommerziell
Datum der Freischaltung:12.08.2016
Referierte Publikation:Ja
Datum der Eintragung als referierte Publikation:16.08.2016
Schriftenreihen ohne Nummerierung:Wissenschaftliche Artikel der BAM