Amine-assisted facetted etching of CdSe nanocrystals.
The treatment of CdSe nanocrystals (NCs) in a 3-amino-1-propanol (APOL)/water (v/v = 10:1) mixture at 80 degrees C in the presence of O(2) causes them to undergo a slow chemical etching process, as evidenced by spectroscopic and structural investigations. Instead of the continuous blue shift expected from a gradual decrease in NC dimensions, a bottleneck behavior was observed with distinct plateaus in the peak position of photoluminescence (PL) and corresponding maxima in PL quantum yield (i.e., 34 +/-7%). It is presently argued that such etching behavior is a result of two competitive processes taking place on the surface of these CdSe NCs: (i) oxidation of the exposed Se-sites to acidic SeO(x)() entities, which are readily solubilized in the basic APOL/H(2)O mixture, and (ii) coordination of the underlying Cd-sites with both amines and hydroxyl moieties to temporally impede NC dissolution. This is consistent with the HRTEM results, which suggest that the etched NCs adopt pyramidal morphologies with Cd-terminated facets (i.e., (0001) bases and either {011} or {21} sides) and account for the apparent resistance to etching at the plateau regions.
Li
Rongfu
R
Nanomaterials Optoelectronics Laboratory, Polymer Program, Department of Chemistry, Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269, USA.
Lee
Jeunghoon
J
Yang
Baocheng
B
Horspool
David N
DN
Aindow
Mark
M
Papadimitrakopoulos
Fotios
F
D000588:Amines / Q000737:chemistry*; D019187:Cadmium Compounds / Q000737:chemistry*; D049449:Luminescence; D049329:Nanostructures / Q000737:chemistry*; D009943:Organophosphorus Compounds; D009994:Osmolar Concentration; D010084:Oxidation-Reduction; D018036:Selenium Compounds / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet
D000588:Amines; D019187:Cadmium Compounds; D009943:Organophosphorus Compounds; D018036:Selenium Compounds; C044965:trioctyl phosphine oxide; C058667:cadmium selenide