Effect Of Complexants On The Microstructure And Properties Of Zno Thin Films

Zinc oxide(ZnO) is aⅡ—Ⅵwurtzite structured semiconductor posses a direct wide band gap of 3.37 eV. As ZnO the large exciton binding energy of 60 meV at room temperature, it is a versatile material and has emerged as a promising candidate after GaN wide bandgap semiconductor for wide applications in the fields of ultraviolet emission devices. Since more than 90%visible light transmittance and good electrical conductivity, ZnO is also used in transparent electrodes, solar cell windows.In addition, ZnO has a competitive photocatalytic activity greater in some cases than TiO2:for example, on the discoloration of Reactive Blue 19, a textile anthraquinone dye, in aqueous suspension and in the oxidation of protocatechuic acid. Most of the researchers modify powder ZnO by doping materials or semiconductor compounding. But the powder ZnO has many disadvantages such as easy inactivation, easy reunification, and difficult reclamation and so on. All these limit severely its practical application. Therefore, nano-crystalline ZnO immobilization techniques become an important aspect of photocatalytic development.So far, the impacts of the thickness, the calcination temperature, concentration, and sol PH value to the microstructure and properties of ZnO thin films were studied. But little work was done on the effect of complexants on the ZnO thin films. In this work, a series of ZnO films, zinc acetate as precursor, were deposited on two kinds of glass slide using sol-gel technique by altering the complexants (monoethanolamine,diethanolamine,triethanolamine). X-ray diffraction (XRD), atomic force microscope (AFM), UV-Vis absorption spectroscopy, X-ray photoelectron spectroscopy (XPS) and Photoluminescence (PL) were used to study the effect of complexants on the ZnO thin films and their properties.The results show that,1) MEA/ZnO films show excellent c-axis orientation, main reason is considered as the shorter grain diffusion length.2) the surface morphology of MEA/ZnO thin films show well-defined compact balls and a smaller roughness, main reason is considered as the (002) surface higher orientation.3) The phtocatalytic activities of ZnO films prepared with tree kinds of complexant are in the following order:DEA/ZnO> TEA/ZnO> MEA/ZnO, The higher phtocatalytic activity of DEA/ZnO films caused by relatively better optical absorption property and many oxygen defects.4) The photocurrent of ZnO films prepared with tree kinds of complexant are in the following order:MEA/ZnO> DEA/ZnO>TEA/ZnO。The higher the c-axis preferred orientation the higher photocurrent due to the reduction in the scattering of carriers at the grain boundaties.The results provides a theoretical basis for the based theory of the structure and properties of ZnO thin films, has some significance in the field of ZnO applications.