Preparation And Thermoelectric Performance Of PEDOT:PSS-based Hybrid Fibers

Wearable electronic devices have shown a clear trend toward miniaturization and integration in recent years,which places higher requirements on the device's energy supply system.Thermoelectric material is a functional material that can use the temperature difference between body temperature and room temperature to generate electricity.In recent years,conductive polymers have attracted widespread attention from researchers in the field of flexible wearable devices due to their non-toxic and easy processing characteristics.Commercially available poly?3,4-dioxyethylenethiophene?:poly?sodium p-vinylbenzenesulfonate??PEDOT:PSS?water-soluble dispersion is one of the most promising conductive polymers.Its excellent electrical conductivity and potential stretchability make it show great application prospects in OLED,OFET,OPV and other fields.The current methods for preparing PEDOT:PSS fibers are mainly focused on surface modification and wet spinning.In addition,the gel method is a method for easily producing fiber PEDOT:PSS fiber.However,the electrical conductivity of PEDOT:PSS gel fibers reported so far is low,making it difficult to achieve thermoelectric conversion.How to prepare high-conductivity PEDOT:PSS gel fiber is the key issue to realize wearable thermoelectric conversion.In addition,with the development of energy filtering effects and quantum confinement effects,organic/low-dimensional inorganic composite thermoelectric materials have attracted widespread attention in recent years.Among them,low-dimensional carbon materials including carbon nanotubes?CNTs?and graphene are widely used as fillers for conductive polymers in China because of their high conductivity,large specific surface area,and unique?-?conjugated structure.This provides new possibilities and opportunities for improving the thermoelectric performance of PEDOT:PSS.In this thesis,based on the research on the preparation of highly conductive PEDOT:PSS gel fiber by gel method,it is compounded with highly conductive low-dimensional carbon materials?graphene and single-walled carbon nanotubes?,combined with effective solvent treatment on the fiber surface The composition is adjusted to obtain PEDOT:PSS-based gel fibers with high thermoelectric performance,which provides a reference for the realization of flexible wearable energy collection and supply device assembly.1.A highly conductive p-type PEDOT:PSS fiber was produced by gelation process,which was 3 orders of magnitude higher than that of previous hydrogel fibers.Surprisingly,a posttreatment with organic solvents such as ethylene glycol and dimethyl sulfoxide tripled their electrical conductivity with an only 5%decreased Seebeck coefficient,consequently leading to an optimized thermoelectric power factor.Furthermore,we assembled a p-n-type thermoelectric device connecting five pairs of p-type PEDOT:PSS fibers and n-type carbon nanotube fibers.This fiber-based device displayed an acceptable output voltage of 20.7 m V and a power density of 481.2?W·cm^-2with a temperature difference of?60 K.2.PEDOT:PSS/SWCNT hybrid fibers were synthesized via gelation process,which presenting a 30%enhancement of the electrical conductivity with negligible changes of Seebeck coefficient.Moreover,there was a significant increase in the Young's modulus in accordance with the addition of an appropriate amount of SWCNTs.Thereafter,the as-prepared hybrid fibers were treated using ethylene glycol?EG?to further optimize the TE performance.Moreover,the influence of the treatment time and temperature were systematically investigated.The EG treatment resulted in a significant improvement in the electrical conductivity without a significant decrease in the Seebeck coefficient.Furthermore,the hybrid fibers were subject to EG treatment at elevated temperature,of which the optimal power factor was approximately 30%higher than that of the EG-treated PEDOT:PSS/SWCNT fibers at 25°C.This indicates that the solvent treatment at higher temperature improves the TE performance of hybrid fibers.3.We prepared graphene and PEDOT:PSS hybrid fiber with simultaneous enhancement of electrical conductivity and fracture elongation via hydrothermal process.The optimal electrical conductivity of hybrid fiber was 96.3 S cm^-1,which was about 2 times higher than that of previous reports.Moreover,the fracture elongation doubled as 10.1%after the introduction of PEDOT:PSS.Furthermore,the dominant charge carriers in the hybrid fibers was altered from hole to electron after polyethyleneimine ethoxylated?PEIE?treatment.Finally,a fiber thermoelectric device consisted with 3 pairs of as-prepared p-and n-type hybrid fiber was assembled and the output properties were quantified under a serious of temperature gradient.This work may provide a good reference to achieve highly conductive graphene fiber with enhanced fracture elongation for versatile applications.