| Vinylidene fluoride(VDF)-based polymers are an important member of functional materials.Due to its unique electrical activity,excellent flexibility,good processability,long-term stability,and biocompatibility,it has broad applications in flexible electronics,such as electrical energy harvesting,electronic information storage,and human-computer interaction systems.The outstanding electrical activity of the vinylidene fluoride polymers comes from the change of its inherent electric dipoles in response to external stimuli,including sound,light,heat,force,and electric field.Thus,they can realize the coupling and conversion of various physical quantities.Based on the energy conversion mechanism,it is a key issue to realize the design and control of materials and structure to achieve optimized function and expansion of applications in the development of flexible electronic devices.The thesis focuses on the coupling and conversion behaviors of the VDF-based polymers between different forms of the energies.Combined with the design of the materials and structure,we explore the remote energy harvesting and flexible wearable sensor.The research contents are summarized as follows:1.The photo-thermo-electric nanogenerator based on molybdenum disulfide/pyroelectric polymer nanocomposite and its physical mechanismsThe energy problem arises from the contradiction between the increasing energy demand of human beings and the limited energy resources,and restricts the development of our society.The exploitation of energies,such as light,heat,etc.,extensive in the environment is a destined trend in resource utilization.To this end,we select molybdenum disulfide(Mo S2)with excellent light-to-heat conversion property and ferroelectric polymer with pyroelectricity,and fabricate the light-responsive nanocomposite films by solution casting.The nanocomposite film has a wide spectral absorption range and excellent photothermal conversion effect,and its response to nearinfrared light is particularly sensitive.A sandwich-structured photo-thermo-electric nanogenerator(PTENG)is prepared by vapor deposition of silver electrodes.Under irradiation of 915 nm near-infrared light,the device has a voltage output of 59 m V and a current of 0.84 n A.Through observation of photothermal and photoelectric behavior,as well as finite element simulation,we demonstrate that the photoelectric signal in the PTENG comes from the coupling of the photothermal effect of molybdenum disulfide and the pyroelectric effect of ferroelectric polymer.In addition,the pyroelectric performance can be improved by adjusting the external light intensity,the content of molybdenum disulfide,and the film thickness.This provides ideas on the development of next generation of energy conversion devices and nanogenerators.2.Skin-inspired flexible mechanical transducer with two-dimensional titanium carbide/ferroelectric polymer nanocomposite as the active layerAs an interface between the next generation of electronics and biological tissues,wearable electronic devices have always attracted extensive attention.The construction of sensor devices with high sensitivity and wide response range is still a great challenge.Based on the high electromechanical coupling properties of the ferroelectric polymer,an active layer with high dielectric permittivity is obtained by incorporation of MXene,a two-dimensional conductive material.At the same time,a simple sandpaper is used as a template to construct a micro-spinous shaped protrusion structure similar to the Merkel disks under the human epidermis.Benefit from the synergistic effect of the high electroactive layer and the biomimetic microstructure,the transducer exhibits a series of excellent response behaviors,including higher sensitivity(~16 k Pa-1),lower detection limit(~8.9 Pa),wide response range(0.0089-89 k Pa),and fast response time(? 230 ms).In addition,due to the excellent flexibility and stability,the device can detect series of dynamic signals in different scenarios such as physical activities and voice recognition,which is a promising competitor in the field of flexible electronics. |
PDF Full Text Request