Semiconductor Encapsulation Of Cu Nanowires And Commercial Fabrication System For Flexible Transparent Electrodes

With the popularity of optoelectronic technologies such as smart phones,curved displays,and flexible wearables in daily life,the development of next-generation optoelectronic devices has become one of the most concerned topics,in which"flexibility" and "large area" are the key issues.These two keywords also represent the related challenging problems influencing the development of advanced optoelectronic materials.Transparent electrodes,as an indispensable part of optoelectronic devices,require higher matching requirements for future research in optoelectronic technology.In order to search for new ideas and solutions,this thesis was carried out with a systematic theoretical and experimental research work based on the synthesis of metalsemiconductor core-shell heterostructure nanowires,ultra-fast ultraviolet pulse laser scanning to fabricate Cu NWs transparent conductive films,and commercial production of transparent electrodes and application in flexible touch screens.Firstly,the Cu NW with one-dimensional structure is used as a platform,and related semiconductor material is directly coated on the surface.We designed the onepot liquid phase method,and optimized the reaction temperature to synthesize coppermetal core-shell nanowires with ultra-high aspect ratio,smooth surface and uniform dispersion,determining controllable parameters to regulate the thickness of the metal shell.After that,the metal shell layer is subjected to high-temperature nitriding treatment.We complete the conversion from the metal to corresponding nitride semiconductor layer,and successfully realize the preparation of Cu-based nitride semiconductor(GaN,AlN)core-shell heterostructure nanowires.Heterostructured NWs keep in high transmittance,good electrical conductivity,and excellent stability at room temperature and extreme environments.The most important thing is to obtain the corresponding photoluminescence characteristics of AlN and GaN,maintaining good basic material properties.The successful preparation of metal-semiconductor core-shell heterostructure NWs has provided a very important research basis for the fabrication of functional heterostructure semiconductor devices,which further expands the Cu nanowire structure system and functional application fields.Secondly,a rapid UV pulse laser scanning technology was proposed to realize the conductivity treatment of Cu NWs.Aiming at the welding process mechanism of light treatment,we use the finite element method to establish the related model and simulate the photothermal field,to explore the influence of light in different wavelength on the heat distribution.It is found that as the wavelength becomes shorter,there is a high thermal effect at the node.Then,according to theoretical results,the UV laser irradiation was chosen to conduct on Cu NWs to remove surface organic residues with high heat generation,and realize fusion welding at the junction of Cu nanowires.Rapid conductive welding process under annealing-free room temperature environment could be completed with a single pulse in only 10 ms.At the same time,the formation of a uniform planar network with excellent photoelectric performance is achieved,resulting in excellent conductivity(33 ohm/sq@87%transmittance at 550 nm).Furthermore,inspired by the concept of the new impression pointillism oil painting,we designed a variable axis motion control laser scanning device to realize the preparation of ultra-large area TCEs and fine-patternable Cu NW working circuits.The transparent conductive electrode with a large area of 20×20 cm2 could be prepared in about 3?4 minutes.With UV laser scanning technology,we have successfully prepare a new type of fully transparent LED chip with ultraviolet and blue light,exhibiting excellent photoelectric performance.That perfectly matches the requirements of device applications and greatly expands the industrial application prospect of Cu NWs TCEs.Thirdly,the technology of commercial preparation of Cu NWs TCEs has been studied,and the fabrication of fully transparent flexible touch screens was achieved.We have designed a continuous growth equipment for the mass synthesis of liquidphase nanomaterials,which greatly improves the synthesis yield of Cu NWs in high quality(Aspect ratio>2000).Next,we built 3D ultrasonic spraying system to rapidlly prepare large-area Cu NWs transparent conductive films.And various influencing factors on the spraying process were fully studied,which help to optimize the quality of sprayed Cu NW planar network film.Then,with a resistive touch structure and Cu nanowire transparent conductive film,we accomplish to manufacture a fully transparent and flexible smart touch screen.We have completed smooth writing tests with the touch screen in both flat and curved states and achieved high-precision touch sensing.By designing and building a continuous growth device and a 3D ultrasonic spraying system,the industrialized preparation of ultra-large area Cu NWs TCEs could be achieved.Its excellent performance in flexible touch screens also provides a novel idea for the manufacture and realization of new flexible optoelectronic devices.The research results reveal important scientific guidance for the exploration and development of new photovoltaic devices in the future.It proves that flexible transparent electrodes based on Cu NWs have shown great application potential in the research of photovoltaic technology.