The Properties Of PEDOT Thermoelectric Materials Based On Vapor Phase Polymerization

As the energy shortage and environmental pollution getting increasingly dominant,new energy sources raise worldwide attention.Thermoelectric material can directly convert heat into electric energy via the transportation of carriers to achieve effective utilization of low-grade thermal energy from industrial waste heat or body.At present,inorganic thermoelectric materials have been deployed into commercial application,of which further improvement was,unfortunately,hindered by their low abundance,high cost and rigorous processing condition.Hence,researchers turn their subjects into organic conductive polymer out of high abundance,outstanding flexibility as well as excellent processability.Poly?3,4-ethylenedioxythiophene??PEDOT?triggered extensive attention due to its well mechanical properties,intrinsic low thermal conductivity and adjustable electrical conductivity.Intrinsically conductive polymer combines electronic properties of mental with stretchability and flexibility of polymer,so it is of great significance to develop highly efficient fabrication method to obtain intrinsically conductive polymer.Vapor-phase polymerization?VPP?is an efficient method to fabricate highly conductive intrinsic polymer for easy operation and little limitation on substrate.Current researches were mainly focused on polymerization mechanism,essential parameter in polymerization process and regulation in polymer performance.Meanwhile polymer design and application are also important development directions.This work mainly discusses PEDOT-based thin film and electronic textile fabricated via VPP.The major contents are as follows:1.In this work,the effects of additives and post-treatment solvents on the thermoelectric?TE?performance of VPP-PEDOT films were systematically investigated.The use of 1-butyl-3-menthylinidazolium tetrafluoroborate ?[BMIm][BF₄]?was shown to significantly enhance the electrical conductivity of VPP-PEDOT films compared with other additives.The introduction of EG into oxidant solution could elevate Seebeck coefficient of PEDOT film.The VPP-PEDOT film post-treated with mixed ethylene glycol?EG?/[BMIm][BF₄]solvent displayed the high power factor which is 122%higher than that prepared without any additive or post-treatment solvent,along with enhanced electrical conductivity and Seebeck coefficient.This work highlighted the superior effect of the [BMIm][BF₄]for additive and solvent post-treatment on the TE performance of the PEDOT film.2.In this work,we employed low toxic reductant polyethylenemine?PEI?to treat PEDOT thin film.Two steps were involved:the PEDOT film was firstly treated with H₂SO₄ and subsequently with PEI hybrid solution in high boiling point solvents?DMSO,DMF NMP and EG?.A series of characterizations were used to detect the changes on changes of crystalline structure and oxidation level and the effect of these changes upon thermoelectric performance of PEDOT thin film.It was demonstrated that the thermopower of well-ordered crystallites in the PEDOT film significantly increases more than five times(from 11 to 59?V K^-1)by the PEI/DMF solution immersion process,while the electrical conductivity is maintained at 100 S cm^-1.3.Advanced wearable organic electronics have been widely studied for flexible textile-based strain sensors.However,two main issues to be addressed in wearable electronic sensors are the poor electron transfer under tensile conditions and water durability.In this work,we proposed an efficient strategy for the fabrication of a highly conductive commercial textile coated with PEDOT via VPP as a wearable thermoelectric?TE?strain sensor.The PEDOT-coated textile exhibited excellent mechanical elasticity and electrical properties in response to external strain.An optimized gauge factor?GF?of the strain sensor reached 54 at a strain of 1.5%,which has the capability to fully satisfy the demands of wearable electronic sensor devices.More importantly,the strain sensor showed a good strain after cyclic loading of an external stress.Besides,a large output voltage of 5.0 mV was achieved at a temperature gradient??T?of 25 K,which is promising for textile generator applications.