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(a) Quantum confinement leads to an enhanced recombination of photogenerated electron–hole pairs inside a core QD. (b) Photocharge generation is enhanced in a type-II core/shell structure QD by separating electron–hole pairs and delocalizing them in the core and shell region, respectively. (c) Schematic of the device architecture used to measure photorefractivity.
Absorption and PL spectra of CdSe core QDs (dotted line) and CdSe/CdTe type-II QDs (solid line) in chloroform. The inset shows a TEM of the CdSe/CdTe QDs. The scale bar is 20 nm.
(a) Absorbance of the of the control sample (solid line), CdSe sensitized sample (dotted line), and CdSe/CdTe sensitized sample (dashed line). The arrow indicates the excitation energy. (b) Photocurrent as a function of the external electric field for the control sample (triangles), CdSe sensitized (squares), and CdSe/CdTe sensitized (circles) polymer composites. The inset shows a plot of the photocharge generation quantum efficiencies in these samples.
(a) Transmitted intensities of the two beams in the CdSe sensitized (stars) and CdSe/CdTe sensitized (open circles) samples at a bias of . One of the two beams is switched on at 5 s and turned off at 26 s. (b) Plots of 2BC net-gain coefficients as a function of the applied electric field. (c) FWM internal diffraction efficiencies as a function of the applied electric field. Squares and circles are data for CdSe sensitized and CdSe/CdTe sensitized composites, respectively. The inset shows a plot of the refractive-index construction time as a function of the applied electric field.
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