Investigation Of Nano Generators Based On ZnO Nanotube Arrays

Zinc oxide (ZnO) has a band gap of 3.4 eV and an exciton binding energy of 60 meV at the room temperature. Because of the super thermostability and unique mechanical, optical and electrical property, ZnO is one of the most important function materials for applications in electronics, optics, optoelectronics, laser and LED. ZnO is relatively biosafe and biocompatible, and it can be used for biomedical applications with little toxicity. Due to its exceptional semiconducting, piezoelectric, and pyroelectric properties, ZnO is a unique material that has great potential applications in nanoelectronics, optoelectronics, sensors, field emission, light-emitting diodes, photocatalysis, nanogenerators, and nanopiezotronics. Vertically aligned ZnO nanowires have a variety of astonishing applications in electronics, optoelectronic, and electromechanical nanodevices. Therefore, fundamental understanding about the growth of ZnO nanowire arrays is of critical importance for controlling their size, composition, structure, and corresponding physical and chemical properties. In this paper, the controlled fabrication of ZnO nanotube arrays is achieved on different substrates in order to explore the applications of ZnO nanomaterials in piezoelectric generator and solar cell. The main points are as follows:â‘ Nano devices based on nanoarrays have been attracted great attentions of researches world wide. There are differences in functions between 1D hollow structure and nanowire. However, we meet great difficulty to fabricate nanotube arrays compared with the fabrication of nanowire arrays. Here, hexagonal ZnO nanotube arrays were synthesized on the GaN, gold, fiber and ITO substrate by a low temperature solution chemical method. The method divides into two temperature steps including the synthesis nanowire arrays in a higher temperature and etching the nanowire arrays into the nanotube arrays in a lower termperature. The control of dimension and density of the ZnO nanotube arrays were investigated under different growth conditions, such as the growth time, temperature and concentration of nutrient solution. The vertical orientation ZnO nanotube arrays with uniform size were obtained. The formation mechanism has been investigated and the general principle for the synthesis of nanotube arrays has been found.â‘¡It is desperate to develop nanotechnology that harvests energy from the environment for self-powering nanodevices. Due to the special structure of nanotube, the different potential from piezoelectricity can be naturally divided by the hollow of tube when the nanotube is bent and deformed, which might enhance output voltage. Here, based on the piezoelectric property of ZnO, the piezoelectric property of ZnO nanotube arrays was measured by AFM using a Pt coated Si tip in contact mode. The detailed profile of the observed electric output was understood based on the calculated piezoelectric potential in the nanotube with consideration of the Schottky contact formed between the metal tip and the nanotube, and analysis of the data collected from AFM.â‘¢To eliminate the use of AFM, generate electricity simultaneously and continuously from all the nanorubes and realize the continuous output power of piezoelectric device based on the ZnO nanotube arrays, the Pt coated ZnO nanotube arrays were employed as numerous parallel tips of AFM, and the piezoelectric generator were fabricated by occluding the Pt coated and uncoated ZnO nanotube arrays. The coutinuous output power was obtained using ultrasonic vibration to drive the motion of the nanotube arrays.â‘£The increasing demand for fossil fuels and the environmental impact of their use are continuing to exert pressure on an already-stretched world energy infrastructure. The renewable energy sources have become one of the major concerns of the world. ZnO has a band gap of 3.4 eV. Since ZnO nanotube arrays have good light absorption and adsorption dye capability, it is a high quality anodic material for the dye-sensitized solar cell (DSSC). Here, the dye-sensitized solar cell (DSSC) have been fabricated based on the ZnO nanotube arrays on the fiber and ITO substrate, their power conversion efficiencis were comparatively investigated with DSSC of ZnO nanowire arrays.