Stable inp quantum dots with thick shell coating and method of producing the same

[0286]The deposition of a thick ZnSe / ZnS multi-layered shell on a green InP core using zinc oleate, tri-n-butylphosphine selenide, and octanethiol as precursors at temperatures exceeding 280° C. is described. Synthesis of a green InP core is disclosed in U.S. Patent Appl. Publication No. 2014 / 0001405.

[0287]The stoichiometry was calculated for InP cores with an absorption peak at 470 nm, a concentration in hexane of 66.32 mg / mL, and a shell thickness of 3.5 monolayers of ZnSe and 4.5 monolayers of ZnS. Zinc oleate was prepared from zinc acetate and oleic acid as a solid. TBPSe was prepared from selenium pellets and tri(n-butyl)phosphine.

[0288]To a 250 mL 3 neck round-bottom flask was added 3.48 g (5.54 mmol, 13.38 equivalents) of zinc oleate and 33.54 mL of 1-octadecene at room temperature in air. The flask was equipped with a stir bar, a rubber septum, a Schlenk adaptor, and a thermocouple. The flask was connected to a Schlenk line via a rubber hose. Inert conditions were establi

[0295]The deposition of a thick ZnSe / ZnS multi-layered shell on a green InP core using zinc oleate, tri-n-butylphosphine selenide, and octanethiol as precursors at temperatures exceeding 280° C. is described. The resultant nanostructure had a target shell thickness of 1.5 monolayers of ZnSe and 2.5 monolayers of ZnS.

[0296]To a 100 mL 4 neck round-bottom flask was added 0.409 g (0.651 mmol, 3.1 equivalents) of zinc oleate and 2 mL of 1-octadecene at room temperature in air. The flask was equipped with a glass stopper, a rubber septum, a Schlenk adaptor, and a thermocouple. The flask was connected to a Schlenk line via a rubber hose. Inert conditions were established by at least three cycles of vacuum (<50 mtorr) and nitrogen flushing. The mixture was heated to 80° C. under nitrogen flow to afford a clear solution. The temperature was maintained and the flask was put under vacuum once again and pumped until no further gas evolution (<50 mtorr) was observed. The heating mantle was remov

[0303]Nanostructures with green InP cores with a target shell thickness of 1.5 monolayers of ZnSe and (A) 4.5 monolayers of ZnS; and (B) 7.5 monolayers of ZnS were prepared using the synthetic method of Example 2 and varying the amount of zinc oleate and octanethiol added to the reaction mixture. The following amounts of zinc oleate and octanethiol precursors were used to prepare the ZnS shell:

(A) for the 4.5 monolayers of ZnS:

[0304]4.47 g of zinc oleate; and

[0305]1.13 mL of octanethiol.

(B) for the 7.5 monolayers of ZnS:

[0306]11.44 g of zinc oleate; and

[0307]2.88 mL of octanethiol.