Fabrication And Properties Of Graphene-based Triboelectric Generator Devices

Since the term of triboelectric generator was put forward in 2012, it has attracted more and more attention because it has many advantages such as the capability to gather and convert tiny and unusable mechanical energy from living environment into electrical energy, the simple structure, facile preparation process and low cost. However, graphenebased triboelectric generator devices are still a new research field.In this thesis, firstly, the graphene-based transparent triboelectric generators(TTGs)were designed and fabricated, based on the working principle of vertical contactseparation mode-based triboelectric generators. Then, the electrical properties of such triboelectric generators were systematical y studied. Finally, three methods to effectively improve the output power density were presented. The main contents and conclusions of the thesis are as follows.1. The effects of electrodes structure on the electrical properties of TTGs were systematical y investigated. Four different TTGs are fabricated with both polyimide(PI) and polyethylene terephthalate(PET) as friction layers, and conventional transparent electrode indium tin oxide(ITO) and graphene film as electrode materials. Subsequently, their electrical properties are measured under the same conditions. The measurement results indicated that TTG with graphene film as top electrode and ITO as bottom electrode has the best performance. It is attributed to the excel ent flexibility of graphene film and the outstanding conductivity of ITO. Therefore, the design of suitable electrode structure can effectively increase the output power density of TTGs.2. The effects of various negative triboelectric charging materials on the electrical properties of TTGs were systematical y investigated. Four TTGs are fabricated with four different negative triboelectric charging materials, i.e. PI, AZ5214 photoresist, polymethylmethacrylate(PMMA) and polydimethylsiloxane(PDMS)), respectively. Afterward, their electrical properties were measured under the same condition. The results demonstrate that both of TTGs with the AZ5214 photoresist and PDMS as negative triboelectric charging materials have the highest output power densities, because both of the AZ5214 photoresist and PDMS have strong electron-accepting ability to generate more net triboelectric charges on surfaces of friction layers. The PDMS is final y selected as the best negative triboelectric charging material for TTGs, after comparing the prices of materials, storage condition, electrical performances and light transmittance of two transparent triboelectric generators.3. The patterned process of PDMS was optimized, and the role of patterned PDMS on the properties of TTGs was investigated. The results show that good PDMS patterns can be obtained with the fluxes of 50 sccm SF6, 10 sccm O2, 10 sccm He, and 10 sccm, the etching power of 160 watts, and the etching time of 10 minutes. The TTG with patterned PDMS has much better performance than that with unpatterned PDMS. This is attributed to the significant increase in the surface roughness of friction layer which will enhance the friction and production of net triboelectric charges, thus improve the electrical performance of the TTGs. It indicates that it is effective to enhance the output power density of TTGs by patterning the friction layer.