The Forming And Performance Optimization Of Novel Micro-nano Conductive Fiber Based Transparent Electrode

Transparent electrodes have broad application prospects in the fields of solar cells,organic light emitting diodes,electronic skin and flexible wearable devices.Conventional indium tin oxide(ITO)transparent electrodes have transmittance >80% and sheet resistance ≤10 Ω/sq,however,their large scale application in flexible electronics and optoelectronic devices is limited by their brittle nature and the scarcity of rare metal indium.Micro-nano conductive fibers are considered as the most promising indium-free transparent electrode materials.This thesis focuses on the forming and performance optimization of micro-nano fiber transparent electrodes.Through fiber composition design and layout structure manipulation,highly conductive micro-nano fiber was produced.The forming techniques of ordered micro-nano conductive fibers were explored to realize the optimization of their photoelectric performance.Finally,a new kind of high-performance indium-free transparent electrode was obtained.Based on the above studies,some meaningful achievements have been obtained:1.By adding Ag nanoparticles to TiN and C conductive fibers,highly conductive micronano composite fibers were formed,which significantly improved the photoelectric performance of the transparent electrode.Ag nanoparticles were continuously distributed inside the fiber to form a conductive path,which increased the conductivity of the fiber by 1-2 orders of magnitude.When the light transmittance of the Ag/TiN fiber transparent electrode achieved 85%,the sheet resistance was only 10 Ω/sq;and the sheet resistance was 22 Ω/sq at >80% transparency.After 1000 bending fatigue tests,the sheet resistance was only increased by 4%,which make it possible to be used as flexible transparent electrode.2.Highly conductive and stable WN was fabricated as a novel material for preparing highly stable transparent electrodes used in extreme environments.When annealing at 900 °C,the WN fiber had good crystallinity and its electrical conductivity was as high as 2189 S/cm.Moreover,the solution electro-writing process was employed to pattern the WN fibers in an ordered structure,and 2.8 Ω/sq at 90% transparency was reached in WN patterns.Based on both high temperature oxidation and acid-base corrosion experiments,it was found that WN fiber has excellent oxidation and corrosion resistance.When oxidated at 160 °C for 16 h,the sheet resistance only increased by 8 %.After acid-base corrosion,the sheet resistance increased by 3.2%.3.The solution electro-writing technology and drawing spinning method were developed to assemble ordered micro-nano conductive fibers,and high-performance transparent electrodes were obtained by manipulating the fiber patterns.10.3 Ω/sq at 90% transparency was achieved in patterned TiN fiber network.After oxidation at 160 °C for 8 h,the sheet resistance increased by 20%;after acid-base corrosion,the sheet resistance increased by only 3.3%.4.The micro-nano W fiber transparent electrode was prepared by draw spinning,and its applications in the field of wearable devices and transparent heaters were explored.At 90% transparency,the sheet resistance of the W fiber electrode was only 0.2 Ω/sq,exceeding the performance of indium tin oxide transparent electrodes.When applied as a wearable heating device,the cycle efficiency was 97% after 100 cycles of electrical heating at 12 V;there was no significant change on the sheet resistance after 200 bending tests.Its electrothermal performance was further studied by water evaporation with a voltage applied,and the water evaporation rate reached 1 ml/min.