Study Of Cuprous Oxide Single Crystal Thin Film Nanogenerators Based On Electrochemical Directional Growth

With the acceleration of global digitalization and the development of electronic devices,some troublesome problems of traditional power supply methods have gradually emerged.Such as the limited battery life and the huge burden of environmental protection brought by the disused batteries.Various factors motivated the scientific and industrial communities to explore a completely new way for power supply.Nanogenerators which emerge as the times require have gradually stepped into researchers’attention.As a p-type metal oxide semiconductor with suitable band gap,high hole mobility and light absorption coefficient and anisotropic crystal structure,cuprous oxide（Cu₂O）has become a research object of great interest in the field of optoelectronics.In this thesis,from the controlled synthesis technique of Cu₂O,the response characteristics of crystal structures with different growth directions on the optoelectronic properties were systematically investigated;And then,the impact of the configuration of the device structure on the direction of the electromechanical signal output was intensively studied.And the related principles were also elaborated in detail.The main research conducted consists of the following:（1）The effects of electrolyte alkaline strength and deposition potential on the crystalline quality and crystal growth direction of thin films were systematically investigated during the preparation of Cu₂O films by electrochemical deposition.The Cu₂O particles grow regularly along the{100}direction,showing a tetragonal structure with exposed{111}crystal faces when p H is stabilized in the weak alkaline range from 7 to 8.And under the strongly alkaline conditions（11<p H<12）,the Cu₂O particles grow regularly along the{111}direction,showing a triangular structure with exposed{100}crystal faces,realizing a controlled synthesis technique for Cu₂O single-crystal films.Furthermore,the photovoltaic test results of{111}-oriented Cu₂O and{100}-oriented Cu₂O showed that the Cu₂O single-crystal films grown along the{111}direction showed a better charge separation properties than those grown along the{100}direction by virtue of lower charge transfer resistance and the faster electron and hole separation effect.Therefore,{111}-oriented Cu₂O is more suitable to be a key research object in the field of energy conversion.（2）Flexoelectric nanogenerators with{111}-oriented Cu₂O single-crystal thin films were proposed and fabricated,which could output a continuous direct current signal.And it can be applied to human body sensors and used to provide power supply for small power appliances,successfully.{111}-oriented Cu₂O single-crystal thin films was prepared by electrochemical deposition on flexible PET substrate coated with ITO,and then Pt electrode was sputtered on PET/ITO/{111}-oriented Cu₂O by magnetron sputtering.The Schottky contact was successfully constructed between Pt and Cu₂O.And finally organosilicon was used to complete the encapsulation of the nanogenerator by casting method.Intensive studies have revealed the necessity of device structures with Schottky contact for unidirectional signal output and the close dependence of the polarization direction of the polarized charge on the output signal duration.The accumulated flexoelectric built-in electric field formed in the 2-D Cu₂O single-crystal film flexoelectric nanogenerator is consistent with the output direction in the bend state,leading to a continuous,stable and high-power density of 14.4μW cm^-2.The comparative analysis demonstrates that the 2-D Cu₂O single-crystal film flexoelectric nanogenerator can not only outperform conventional single-component piezoelectric nanogenerator but also offer substantial application potentials in the development of continuous power generators and motion behavior tracers.