液相沉积法制备ZnO/CdS复合纳米棒阵列薄膜及其光电性质

采用两步化学溶液沉积法在氧化铟锡(ITO)导电玻璃衬底上制备了ZnO/CdS复合纳米棒阵列薄膜.利用X射线衍射(XRD)仪、扫描电子显微镜(SEM)、紫外-可见(UV-Vis)吸收分光光度计、荧光(PL)光谱仪及表面光电压谱(SPS)研究了不同CdS沉积时间对复合薄膜的晶体结构、形貌、光电性质的影响.研究结果表明:ZnO纳米棒阵列表面包覆CdS纳米颗粒后,其吸收光谱可拓展到可见光区;与吸收光谱相对应在可见光区出现新的光电压谱响应区,这一现象证实,通过与CdS复合可显著提高ZnO纳米棒阵列在可见光区的光电转换性能;随着CdS纳米颗粒沉积时间的延长,复合纳米棒阵列薄膜在大于383nm波长区域的光电压强度逐渐减弱,而在小于383nm波长区域的光电压强度逐渐增强.用两种不同的电荷产生和分离机制对这一截然相反的光响应过程进行了详细的讨论和解释.

Solution Based Synthesis of ZnO/CdS Composite Nanorod Array Film and Its Photoelectric Properties

Well-aligned ZnO/CdS composite nanorod array film was grown on an indium tin oxide (ITO) substrate by two-step chemical solution deposition method. The effects of CdS deposition time on the crystal structure, morphology, and photoelectric performance of the ZnO/CdS composite film were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible absorption spectroscopy (UV-Vis), photoluminescence spectroscopy (PL), and surface photovoltage spectroscopy (SPS). Results showed that the absorbance of the composite film extended into the visible region compared with the bare ZnO nanorod arrays. SPS also showed a new response region corresponding to the absorption spectrum. This result indicated a remarkable photoelectric conversion efficiency improvement in the visible region. We also found that the SPS response intensity of the composite film decreased gradually above 383 nmwith an increase in CdS deposition time. However, the SPS response intensity increased below 383 nm. We interpreted this phenomenon using two distinct photoinduced charge generation and transfer mechanisms.