Preparation And Research On Properties Of Flexible Organic/Inorganic Composite Thermoelectrical Films Based On PEDOT:PSS

With the rapid development of wearable electronic devices,the demands for flexible and integrated portable power supplies of electrical devices are getting higher and higher.Thermoelectric（TE）material can directly convert thermal energy into electric energy,which has great potential in the field of TE power generation.Conductive polymer material poly（3,4-ethylenedioxythiophene）:-poly（styrenesulfonate）（PEDOT:PSS）is the first choice due to its advantages of low cost,easy production and low thermal conductivity.However,the TE properties of PEDOT:PSS are inferior to inorganic TE materials,which cannot meet the needs of power supply equipment.In recent years,researchers have carried out some studies to improve the properties of PEDOT:PSS with composite inorganic TE materials,which has opened up a new direction for the development of TE materials,but also provides the possibility for the further development of wearable electronic devices.SnSe and Cu₂S have been widely concerned due to their high Seebeck coefficients.MWCNTs have high electrical conductivity and their TE properties can be greatly improved by combining the materials with high Seebeck coefficients.Inorganic TE materials SnSe,MWCNTs and Cu₂S were composited with PEDOT:PSS to make it have better flexibility and higher TE properties.The main conclusions of this paper are as follows:（1）Firstly,the vacuum assisted filtration method was used to prepare SnSe/PEDOT:PSS composite films supported by nylon membrane.The TE properties of the composite films were studied by changing the SnSe contents and temperatures.When the SnSe content reached 10 wt%,the maximum power factor of composite film obtained at 353 K,which was24.42μW m^-1k^-2.10 wt%SnSe/PEDOT:PSS composite film has a good flexibility after bending 1000 times on the radius of 4 mm iron rod,the relative resistance only increases by9%.The maximum output power of a TE generator consisting of 3-leg with optimal SnSe/PEDOT:PSS composite film is 13.37 n W at a temperature gradient of 50 K.（2）Secondly,different contents of MWCNTs were combined based on 10 wt%SnSe/PEDOT:PSS through vacuum assisted filtration method,and then the MSPPD ternary composite films supported by nylon membrane were obtained.The effects of different temperatures on the TE properties of MSPPD ternary composite films were studied.When the content of MWCNTs reached 10 wt%,the maximum power factor of the MSPPD ternary composite film was 59.35μW m^-1k^-2.Then,the MSPPD10 ternary composite film was cold-pressed by different pressures.After 10 MPa pressure treatment,the maximum power factor reaches 166.5μW m^-1k^-2,which is 2.8 times of that non-cold-pressing treatment.As a contrast,the properties of MSPPD0 and MPPD10 composite films after cold-pressing at 10MPa was studied.It was found that MWCNTs/SnSe could enhance the TE property better than MWCNTs or SnSe combined with PEDOT:PSS alone.The open-circuit voltage and the maximum output power of the flexible TE generator made of 4-leg MSPPD10 ternary composite films by 10 MPa cold-pressing are 2.7 m V and 13.5 n W at a temperature gradient of 30 K,respectively.（3）Finally,A self-supporting Cu₂S/PEDOT:PSS composite film was prepared by vacuum assisted filtration method.The effects of different ratios of Cu₂S and temperature on the TE properties of Cu₂S/PEDOT:PSS composite film were studied.The maximum power factor of10 wt%Cu₂S/PEDOT:PSS composite film is 56.15μW m^-1k^-2 at 393 K.After cold pressing at4 MPa pressure,the power factor of the composite film is increased to 115.08μW m^-1k^-2,which is 2.1 times of that non-cold-pressing treatment.When the temperature gradient is 30 K,the open-circuit voltage of the TE generator composed of four cold-pressed composite films is2.3 m V,and the maximum output power is 23.06 n W.