چكيده به لاتين
In this work, two main aims have been investigated: a) the fabrication of a piezoelectric nanogenerator and b) the investigation of the piezo-phototronic effect on the performance of the UV photodiode. In order to achieve the first aim, a definition of the piezoelectric property of the material and its applications, especially the fabrication of the piezoelectric nanogenerator, was presented. After the comparisons between semiconductor materials that have piezoelectric properties, zinc oxide nanowires were chosen to fabricate a piezoelectric nanogenerator. Synthesis and growth of the ZnO nanowires was performed by the hydrothermal method on flexible PET/ITO substrate. To improve the piezoelectric property of the ZnO nanowires, some parameters such as the volume of the growth solution in the autoclave during the hydrothermal process were discussed and investigated for the first time, and the optimal values of the mentioned parameters were determined after SEM, XRD and I-V analysis. The obtained results showed that well-aligned ZnO nanowires with high quality crystal structure were grown on the flexible PET/ITO substrate. Finally, after performing the piezoelectric charactrization, it was found that under the application of an external force, the piezoelectric voltage and current equal to 0.85 mV and 44 μA were obtained, respectively, which are comparable with previous research of similarly fabricated devices based on ZnO nanostructure. In the second part of this project, the piezo-phototronic effect was studied and it was theoretically shown how it can affect the performance of the optoelectronic devices, especially photodiodes. To prove this claim, first, a flexible UV photodiode based on ZnO nanowire was fabricated. For this purpose, well-aligned ZnO nanowires and ZnO/PPy composite were grown on the carbon clothe substrate by electrochemical method. Then, SEM, XRD, UV-Vis, and I-V analyzes were performed in to characterize the structural, optical and electrical properties of the UV photodiode. Finaly, by applying external tensile and compressive strains, the piezo-phototronic effect on the performance of the UV photodiode was investigated and it was found that for the desired structure and with the arrangement defined in this research, applying compressive strain can lead to improve the performance of the ZnO/CC and ZnO/PPy-based UV photodiode.
