第三节 有机/无机杂化膜材料
如何使纳米微粒表面带有电荷
(1) 通过调节体系的pH值,使纳米微粒表面原子发生质子化或去质 子化使微粒带上电荷. 如FeO,Fe2O3,Fe3O4@SiO2, Ag@SiO2, MoO(纳米簇),石墨氧化物,黏土板 (2) 控制形成微粒的阴,阳离子的化学计量比偏离1:1,这种方法适 用于沉淀溶度积较大的沉淀体系. 如表面带有负电荷的水溶性 PbI2纳米微粒 (3) 通过吸附带有电荷的小分子使微粒表面带有电荷.如Au,Ag, CdS等 (4) 使用双官能团分子修饰微粒表面,其中一个官能基团与纳米微 粒表面结合为微粒提供稳定性,而另一个指向周围介质的官能 基团为微粒提供表面电荷.如CdS,CdSe,CdTe,HgTe等纳 米微粒表面修饰上电荷.
纳米微粒的层状组装 In optical, electrical and magnetic devices, NPs will be mostly used as thin films. Currently, such films are typically made by spin coating, spraying, or sometimes by simple painting of nanoparticle–matrix mixtures.
硬脂酸
带负电荷的 PbI2 纳米微粒
双极性吡啶盐(PyC6BPC6Py)
N Br
(H2C)6
O
O
(CH2)6 Br
N
J. Chem. Soc., Chem. Commun., 1994, 2777-2778
Nanorainbows: Graded Semiconductor Films from Quantum Dots The graded NP films were assembled using four different CdTe dispersions with luminescence maxima at 495– 505 (green), 530–545(yellow), 570– 585(orange), and 605–620 nm(red) . Layer-by-layer assembly was carried out on glass and plastic substrates and typically 5–10 CdTe NP bilayers of each of four luminescent colors were deposited.
三基色:red, green, blue
J. Am. Chem. Soc. 2001, 123, 7738-7739
Luminescence spectra of (a) exemplary CdTe NPs used in this work and (b) thin films obtained after the sequential deposition of five bilayers of (1) "green", (2) "yellow" (3) "orange", and (4) "red" CdTe.
To evaluate the internal structure of the gradient CdTe film, it was assembled on a flexible cellulose acetate substrate as described in ref 11. A cross-sectional slice of the NP stack was analyzed by transmission electron microscopy (TEM). The asymmetry of the film could be seen in the Transmission electron microscopy images difference of electron diffracting power of the "red" and "green" sides of cross-sections of a graded film made of the assembly (Figure 3a,b). The from five bilayers of "green", "yellow", layers of bigger NPs appear and "red" (total 15) NPs with different noticeably darker in the TEM image magnification." due to the greater percentage of heavier elements on this side of the multiplayer stack.

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