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0957-K07-20

Controllable Synthesis of ZnO Nanorod Arrays via Simple Solution-Based Method Patcharee Charoensirithavorn and Susumu Yoshikawa Institute of Advanced Energy, Kyoto University, Uji, Kyoto, 6110011, Japan

ABSTRACT Here we present a convenient solution-based method, which can afford a procedure to easily fabricate highly oriented ZnO nanorods on substrate at relatively low temperatures. The as-synthesized products have been characterized by scanning electron microscopy (SEM) and X-Ray diffraction (XRD). The results revealed that a densely packed and perpendicularly oriented single-crystalline ZnO nanorod arrays grew vertically on the fluorine-doped SnO2 transparent conducting oxide (FTO) glass substrates. In addition, we found that the length of the nanorod could be freely modified by controlling the solution temperature.

INTRODUCTION Recently, nanoscale one-dimensional (1-D) semiconductor materials have drawn a considerable amount of attentions owing to their unique properties and potentials in fabricating nanoscale optoelectronic devices [1-3]. Among them, ZnO semiconductor, with a wide band gap (3.2 eV) and large exciton binding energy of 60 meV at room temperature, is one of the materials gained the most intensive studies as it is a versatile material and has been considerably used for many application including transparent conductive coating [4], electrode for dye-sensitized solar cells[5], gas sensors[6], and electro-and photo-luminescent material[7]. Various techniques

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including vapor-liquid-solid VLS growth [8], chemical vapor deposition (CVD) [9] and electrochemical vapor deposition (ED) [10] etc. have been developed to prepare well-aligned nanowires/nanorods. However, it is still a challenge to develop a simple size-controllable method for fabrication of uniform nanorods arrays that are cost-effective and allow large-scale production. In this work, we report on the fabrication of highly oriented large surface area ZnO nanorods on substrate using a convenient solution-based method. In near future, this low-energy and less-hazardous technique will become more attractive as a possible alternative for high quality nanorod arrays preparation method. EXPERIMENT Arrays of ZnO nanorods were synthesized on fluorine-doped SnO2 transparent conducting oxide (FTO) glass substrate. The procedure consists of two steps. Firstly, zinc acetate in ethanol solution was dropped onto substrates by spin coating, and then the substrates were dried and annealed in order to form the aligned nanocrystal seeds on the substrates. Secondly, vertical ZnO nanorod arrays from the aligned nanocrystal seeds were grown by immersing modified substrates in precursor solution containing Zn(NO3)2 and NaOH at different growth temperature. Finally, the samples were washed by deionized water and dried in air. The

morphology of the nanorods was characterized using scanning electron microscopy (SEM) and its crystal structure was characterized by using X-Ray diffraction (XRD). RESULTS AND DISCUSSION Figure 1 shows typical scanning