title: Engineering InAs(x)P(1-x)/InP/ZnSe III-V alloyed core/shell quantum dots for the near-infrared.
abstract: Quantum dots with a core/shell/shell structure consisting of an alloyed core of InAs(x)P(1-x), an intermediate shell of InP, and an outer shell of ZnSe were developed. The InAs(x)P(1-x) alloyed core has a graded internal composition with increasing arsenic content from the center to the edge of the dots. This compositional gradient results from two apparent effects: (1) the faster reaction kinetics of the phosphorus precursor compared to the arsenic precursor, and (2) a post-growth arsenic-phosphorus exchange reaction that increases the arsenic content. The cores have a zinc blend structure for all compositions and show tunable emission in the near-infrared (NIR) region. A first shell of InP leads to a red-shift and an increase in quantum yield. The final shell of ZnSe serves to stabilize the dots for applications in aqueous environments, including NIR biomedical fluorescence imaging. These NIR-emitting core/shell/shell InAs(x)P(1-x)/InP/ZnSe were successfully used in a sentinel lymph node mapping experiment.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Sang-Wook
authors.initials: SW
authors.lastname: Kim
authors.forename: John P
authors.initials: JP
authors.lastname: Zimmer
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Ohnishi
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Tracy
authors.forename: John V
authors.initials: JV
authors.lastname: Frangioni
authors.forename: Moungi G
authors.initials: MG
authors.lastname: Bawendi
mesh_terms: D000497:Alloys / Q000737:chemistry; D000818:Animals; D001152:Arsenicals / Q000737:chemistry*; D007204:Indium / Q000737:chemistry*; D010720:Phosphines / Q000737:chemistry*; D045663:Quantum Dots; D051381:Rats; D018036:Selenium Compounds / Q000737:chemistry*; D021701:Sentinel Lymph Node Biopsy; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D014961:X-Ray Diffraction; D017967:Zinc Compounds / Q000737:chemistry*
chemical_list: D000497:Alloys; D001152:Arsenicals; D010720:Phosphines; D018036:Selenium Compounds; D017967:Zinc Compounds; D007204:Indium; C076773:indium arsenide; C044696:zinc selenide; C090882:indium phosphide