Preparation And Properties Of Antimony Telluride/Conductive Polymer Composite Thermoelectric Materials

Thermoelectric materials are environmental-friendly functional materials,which can directly convert waste heat into electric energy via the movement of carriers.Sb₂Te₃ is a relatively mature thermoelectric material near room temperature.Graphene has excellent electrical properties.Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)has many advantages,such as good flexibility and low thermal conductivity.Up to now,the research is mainly focused on the compound between the above-mentioned arbitrary two phases,while few work about the research for the three-component thermoelectric composite material has been reported.The main work is shown as follows:(1)Sb₂Te₃ powders and reduced graphene oxide(rGO)/Sb₂Te₃ composite powders were synthetized using a hydrothermal method and one-step reduction method,repectively,and then corresponding bulk materials were prepared by a cold-pressing method.A maximum power factor of 12.36?W/m K² at room temperature was obtained for the cold pressed rGO/Sb₂Te₃ composite bulk material with 0.6 wt.%rGO.Then the cold-pressed bulk materials were annealed at different temperatures.After being annealed at 425?,a highest power factor of 195.5?W/m K² at 175? was achieved for the cold pressed Sb₂Te₃ bulk material.As the content of rGO increased from 0 to 0.6 wt.%,the electrical conductivity of the cold-pressed rGO/Sb₂Te₃ composite bulk materials annealing at 425? first increased and then decreased while the Seebeck coefficient kept increasing,and a highest power factor of265.43?W/m K² at 175? was obtained for the composite bulk with 0.4 wt.%rGO,which was 36%higher than that of the Sb₂Te₃ bulk materials treated under the same condition.(2)The relative densities of the as-preapred Sb₂Te₃ bulk materials continuously increased with the enhancment of hot-pressing sintering temperature and holding time,and the relative density of the Sb₂Te₃ bulk material reached a highest value of 94.89%after hot-pressed sintering for 3 h at 425?.The electrical conductivity of the hot-pressed rGO/Sb₂Te₃ bulk materials decreased from 1873.16 S/cm to 1124.01 S/cm at 25 ^oC,while the Seebeck coefficient first increased and then decreased,as the content of rGO increased from 0.2 wt.%to 0.6 wt.%.A highest power factor of 784.6?W/m K² at 75? was achieved for the hot-pressed rGO/Sb₂Te₃ bulk materials with 0.4 wt.%rGO.The thermal conductivity of the rGO/Sb₂Te₃ bulk materials(with 0.4 wt.%rGO)perpendicular to the pressing direction was in the range of 0.76-0.97 W/m�K(from 25? to 275?),and a highest ZT value of 0.45 at275? was calculated.The ternary rGO/Sb₂Te₃/Na Cl bulk materials were prepared by a hot-pressing method,and then rGO/Sb₂Te₃ three-dimensional framework bulk materials were obtained by removing the pore-forming agent Na Cl.After filling PEDOT:PSS into the rGO/Sb₂Te₃ three-dimensional framework bulk materials,ternary rGO/Sb₂Te₃/PEDOT:PSS bulk composites were achieved.A highest power factor of 122.51?W/m K² at 125? was obtained for the rGO/Sb₂Te₃/PEDOT:PSS bulk composites,which was 6%higher than that of the rGO/Sb₂Te₃ framework bulk(116.2?W/m K²at 125?).(3)The rGO/Sb₂Te₃/SV4/PEDOT:PSS composite films were prepared by a screen printing process,and then the cold-pressing and annealing treatment were used to treat the composite films.The power factors of the rGO/Sb₂Te₃/SV4/PEDOT:PSS composite films decreased with the rGO/Sb₂Te₃ content increasing.For the rGO/Sb₂Te₃/SV4/PEDOT:PSS composite film with 85 wt.%rGO/Sb₂Te₃,the untreated,cold-pressed,and cold-pressed combining annealed treatment samples obtained a highest power factor of 2.96?W/m K²,8.85?W/m K²,and 14.13?W/m K²,respectively,at 375 K.