Department of Chemistry, Center for Materials Innovation, Washington University, St. Louis, Missouri 63130-4899, USA.
Nano Lett. 2010 Jan;10(1):352-7. doi: 10.1021/nl903740p.
CdSe quantum belts (QBs) having lengths of 0.5-1.5 microm and thicknesses of 1.5-2.0 nm exhibit high photoluminescence (PL) efficiencies of approximately 30%. Epifluorescence studies establish the PL spectra to be uniform along single QBs, and nearly the same from QB to QB. Photogenerated excitons are shown to be effectively delocalized over the entire QBs by position-selective excitation. Decoration of the QBs with gold nanoparticles indicates a low density of surface-trap sites, located primarily on the thin belt edges. The high PL efficiencies and effective exciton delocalization are attributed to the minimization of defective {1100} edge surface area or edge-top/bottom (face) line junctions in QBs relative to quantum wires having roughly isotropic cross sections, for which very low PL quantum efficiencies have been reported. The results suggest that trap sites can be minimized in pseudo-one-dimensional nanocrystals, such that the facile transport of energy and charge along their long axes becomes possible.
具有 0.5-1.5 微米长度和 1.5-2.0nm 厚度的 CdSe 量子带（QBs）表现出约 30%的高光致发光（PL）效率。荧光研究表明，PL 光谱在单个 QBs 上是均匀的，并且从 QB 到 QB 几乎相同。通过位置选择性激发，证明光生激子有效地在整个 QBs 上离域。用金纳米粒子修饰 QBs 表明表面陷阱位点密度较低，主要位于薄带边缘。高 PL 效率和有效的激子离域归因于与具有大致各向同性横截面的量子线相比，最小化了具有缺陷的{1100}边缘表面积或边缘-顶/底（面）线结，对于后者，已经报道了非常低的 PL 量子效率。结果表明，在类一维纳米晶体中可以最小化陷阱位点，从而使得沿着它们的长轴进行能量和电荷的易于传输成为可能。
