College of Chemistry, Jilin University, Changchun 130012, People's Republic of China.
Nanotechnology. 2008 Jun 18;19(24):245706. doi: 10.1088/0957-4484/19/24/245706. Epub 2008 May 12.
A vertically aligned array of ZnO nanorods, fabricated on conductive ITO substrate in aqueous solution, was characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), and UV-visible transmission spectroscopy. Surface photovoltage (SPV) techniques based on a lock-in amplifier and a Kelvin probe were both employed to study the photogenerated charges in the system. The effects of ethanol solvent and a liquid-crystalline porphyrin, [5-(para-dodecyloxy)phenyl-10,15,20-tri-phenyl] porphyrin (DPTPP), on the photovoltage enhancement in the ZnO nanorod array were studied via SPV comparison between different irradiation directions on the system. We demonstrate that the ethanol adsorption could induce the space charge region to expand towards the ZnO/ITO interface. In the absence of ethanol, the ZnO nanorod array with the DPTPP adsorption showed enhanced SPV with reduced attenuation rate of photogenerated charge carriers. We found that the separation of photogenerated charges could be further improved by coating the surface with DPTPP and ethanol together. Furthermore, the SPV spectra patterns of the composite system with opposite incident-light directions reveal that the DPTPP molecules adsorbed just at the surface of ZnO nanorods adopt a more monomeric alignment in contrast to the aggregative state in the DPTPP bulk.
在水溶液中，在导电 ITO 衬底上制造的垂直排列的 ZnO 纳米棒阵列，通过扫描电子显微镜（SEM）、X 射线衍射（XRD）和紫外可见透射光谱进行了表征。基于锁相放大器和 Kelvin 探针的表面光电压（SPV）技术都被用于研究系统中的光生电荷。通过比较系统在不同照射方向上的 SPV，研究了乙醇溶剂和液态卟啉[5-（对十二烷氧基）苯基-10,15,20-三苯基]卟啉（DPTPP）对 ZnO 纳米棒阵列光电压增强的影响。我们证明，乙醇吸附会导致空间电荷区向 ZnO/ITO 界面扩展。在没有乙醇的情况下，具有 DPTPP 吸附的 ZnO 纳米棒阵列显示出增强的 SPV，光生载流子的衰减率降低。我们发现，通过用 DPTPP 和乙醇一起涂覆表面，可以进一步提高光生电荷的分离。此外，具有相反入射光方向的复合系统的 SPV 光谱图案表明，吸附在 ZnO 纳米棒表面的 DPTPP 分子采用更单体的排列方式，而不是在 DPTPP 体相中聚集的状态。
