Institute for Microelectronics and Microsystems (IMM-CNR), Unit of Lecce, Via Monteroni, I-73100 Lecce, Italy.
ACS Nano. 2010 Mar 23;4(3):1646-52. doi: 10.1021/nn901575r.
We report on photoconduction and optical properties of aligned assemblies of core-shell CdSe/CdS nanorods prepared by a seeded growth approach. We fabricate oriented layers of nanorods by drop casting the nanorods from a solution on substrates with prepatterned, micrometer-spaced electrodes and obtain nanorod alignment due to the coffee stain effect. The photoconductivity of the nanorod layers can be improved significantly by an annealing process under vacuum conditions. The spectral response of the photocurrent shows distinct features that can be assigned to the electronic level structure of the core-shell nanorods and that relate well to the spectra obtained by absorption measurements. We study assemblies of nanorods oriented parallel and perpendicular to the applied electric field by the combined use of photocurrent and photoluminescence spectroscopy. We obtain consistent results which show that charge carrier separation and transport are more efficient for nanorods oriented parallel to the electric field. We also investigate the light polarization sensitivity of the photocurrent for the oriented nanorod layers and observe higher conductivity in the case of perpendicular polarization with respect to the long axis of the nanorods.
我们报告了通过种子生长法制备的核壳 CdSe/CdS 纳米棒的取向组装的光导和光学性质。我们通过将纳米棒从溶液滴在具有预先图案化的、微米级间隔的电极的衬底上来制备取向层，由于咖啡环效应，纳米棒得到了取向。在真空条件下退火处理可以显著提高纳米棒层的光电导。光电流的光谱响应显示出明显的特征，可以归因于核壳纳米棒的电子能级结构，并且与吸收测量得到的光谱很好地相关。我们通过光电导和光致发光光谱学的组合使用研究了平行和垂直于外加电场取向的纳米棒组装体。我们得到了一致的结果，表明对于平行于电场取向的纳米棒，载流子分离和输运更加有效。我们还研究了取向纳米棒层的光偏振灵敏度，并观察到相对于纳米棒长轴的垂直偏振时具有更高的电导率。
