Highly Conductive PEDOT:PSS Films And Wires And Their Thermoelectric Applications

Conductive polymer PEDOT:PSS has been attracting great attention due to its good optoelectronic and thermoelectric properties,as well as the advantages of mechanical flexibility and easy processing.Applications of the PEDOT:PSS are determined by the properties and shapes.In this thesis,free-standing PEDOT:PSS films and wires with high conductivity have been fabricated based on the understanding of the PEDOT:PSS structure,where sulfuric acid is used to replace PSS to precipitate the PEDOT:PSS.Thermoelectric properties and applications of the free-standing films and wires were demonstrated.The details are as follows:(1)In the aqueous PEDOT:PSS dispersion,PEDOT chains are attached to the long-chain PSS via Columbic interaction and dispersed in water.Based on this structure,a high concentration PEDOT formulation is obtained by droping the PEDOT:PSS dispersion into sulfuric acid solution to replace the PSS,precipitate and then stirring.Then,micronmeter-thick PEDOT:PSS free-standing films were prepared with the formulation.Electrical conductivity around 1400 S/cm and low sheet resistance about 0.6Ω/□were achieved for the free-standing PEDOT:PSS films.(2)PEDOT:PSS wires were fabricated with a wet spinning method by injecting the dispersion into a coagulation bath of concentrated sulfuric acid.PSS on the surface of the PEDOT:PSS drop was replaced by sulfuric acid and thereby conductive PEDOT:PSS wires form.The polymer wire has a conductivity of 1717 S/cm and has good thermal resistance and good stability.The conductivity is stable in air for 98 days(25°C,75%RH),and it is almost unchanged within the temperature range from 220 K to 380 K(the rate of change is-4.4%to 1.2%).(3)Thermoelectric devices were prepared based on the conductive polymer films and wires.Seebeck coefficient and power factor(PF)of the free-standing PEDOT:PSS films are 19.02μV/K and 50.65μW/m K~2;Seebeck coefficient and PF of the PEDOT:PSS wires are 23.14μV/K and 91.94μW/m K~2,which is higher than that of the pristine PEDOT:PSS films through spin-coating(17.34μV/K and 0.04μW/m K~2).Futhermoroe,thermoelectric generators with 34 legs were built on a fabric.It generates a thermoelectric voltage of 2.2 mV by the temperature difference between the hand and air at room temperature.