Alternating layer addition approach to CdSe/CdS core/shell quantum dots with near-unity quantum yield and high on-time fractions

作者：Greytak Andrew B^*; Allen Peter M; Liu Wenhao; Zhao Jing; Young Elizabeth R; Popovic Zoran; Walker Brian J; Nocera Daniel G; Bawendi Moungi G

来源：Chemical Science, 2012, 3(6): 2028-2034.

DOI：10.1039/c2sc00561a

We report single-particle photoluminescence (PL) intermittency (blinking) with high on-time fractions in colloidal CdSe quantum dots (QD) with conformal CdS shells of 1.4 nm thickness, equivalent to approximately 4 CdS monolayers. All QDs observed displayed on-time fractions %26gt;60% with the majority %26gt;80%. The high on-time fraction blinking is accompanied by fluorescence quantum yields (QY) close to unity (up to 98% in an absolute QY measurement) when dispersed in organic solvents and a monoexponential ensemble photoluminescence (PL) decay lifetime. The CdS shell is formed in high synthetic yield using a modified selective ion layer adsorption and reaction (SILAR) technique that employs a silylated sulfur precursor. The CdS shell provides sufficient chemical and electronic passivation of the QD excited state to permit water solubilization with greater than 60% QY via ligand exchange with an imidazole-bearing hydrophilic polymer.

• 出版日期2012