Study On Thermoelectric Properties Of Poly(3,4-ethylenedioxythiophene)/graphene Composites

Thermoelectric materials are green energy materials which can achieve the direct conversion of thermal energy and electric energy.Efficient thermoelectric materials and devices that turn waste heat and low-density energy originated from industrial production and daily life into clean electricity can save energy effectively.Compared with traditional inorganic thermoelectric materials,the organic thermoelectric material,poly(3,4-ethylenedioxythiophene)(PEDOT)have attracted extensive attention due to its low thermal conductivity,simple machining technology,good environmental stability and easy to prepare flexible device.However,research for PEDOT is still in its infancy stage because its thermoelectric performance is far less than inorganic materials.Thus,it’s essential to search for a method to improve the thermoelectric property of PEDOT.Poly(sodium 4-styrenesulfonate)(PSSNa)was used to disperse MWCNT or graphene and acted as dopant and balance agent in the in situ polymerization.Ferric chloride(FeCl3)and ammonium persulfate[(NH4)2S2O8)]were used as the oxidant to induce the polymerization and obtain PEDOT:PSS/MWCNT/graphene(P/M/G)flexible thermoelectric materials.The structures and thermoelectric properties were characterized.As a result,thermoelectric properties of PEDOT:PSS increased with the addition of MWCNT or graphene.The incorporation of both MWCNT and graphene into PEDOT:PSS can promote thermoelectric properties more significant than single component,due to the synergic effects between MWCNT and graphene.The highest power factor of the composites is 0.142 μW/(m K2)at a temperature of 50 ℃ when the contents of MMWCNT and graphene is lwt%,with a mass ratio of 1:1.The fabricated P/M/G hybrids exhibit an improved power factor at room temperature and 50 ℃,corresponding to an enhancement of 72%and 103%compared with the pristine PEDOT:PSS.A self-assembled,micellar soft-template method using SDS as emulsifier and template was used to fabricate 1-D PEDOT nanowires(NWs).After that,2-D graphene was added to PEDOT NWs and the thermoelectric performance of the hybrids was investigated.The influence of reaction conditions on thermoelectric parameters of PEDOT NWs was investigated.Then,thin composite films of PEDOT nanowire/graphene were fabricated through vacuum filtration and the effect of graphene loading was explored.The reaction conditions for PEDOT NWs will affect their thermoelectric performance and the maximum power factor of the PEDOTNW’s was obtained when the molar mass ratio is SDS:FeCl3;:EDOT = 3:2:1,with SDS concentration of 200 mmol/L and a reaction temperature of 50 ℃.The power factor of the hybrids increase with the addition of graphene in the beginning and then decrease.The power factor of the PEDOT nano wire/graphene films reach a maximum at 42.0 μW/(mK2)when the graphene content is 3 wt%.