Fabrication And Optimized Performance Of Large-sized Bi_0.5Sb_1.5Te₃/epoxy Resin Flexible Thermoelectric Films

The flexible thermoelectric thin film device based on Peltier effect has the advantages of small volume,no refrigerant,fast response,and can realize heat transfer in the surface,etc.,it is expected to realize heat dissipation and cooling of micro devices.In this paper,a large-sized flexible Bio.5Sb1.5Te3/epoxy flexible thermoelectric film was prepared by screen printing and hot-pressing curing technology.The effects of hot pressing temperature on the phase composition,microstructure and electrical transport properties of large-scale flexible thermoelectric thin films were investigated.The electrical transport properties of thin films were improved by optimizing slurry composition.The results show that with the increase of hot pressing temperature,the orientation of the films along(0001)surface increases gradually,and the conductivity of the films increases with the increase of hot pressing temperature.When the hot pressing temperature is 573 K,the conductivity of the films reaches a maximum of 7.63×103 S·m-1,and the corresponding maximum power factor reaches 0.53 rriW·K-2·m-1.One advantage of this method,which combines screen printing with hot pressing,is that it can achieve uniform preparation of large thermoelectric thin films.The results show that with the increase of the amount of Bi0.5Sb1.5Te3 powders,the conductivity of the film increases first and then decreases.When the mass ratio(x)of Bio.5Sb1.5Te3 to epoxy system is 8,the conductivity of the films reaches the maximum value of 1.65×104 S·m-1,and the corresponding maximum power factor reaches 1.12 mW·K-2·m-1.Compared with un-optimized samples,the conductivity and power factor of the film increase about 36%and 40%,respectively.The film was tested for flexibility.When the bending radius of the film decreases from 80 mm to 20 mm,the internal resistance of the film remains almost unchanged.When the bending radius is 20 mm,the bending times of the films are less than 3000,The change rate of film internal resistance is less than 5%,which indicates that the films keep good flexibility.The results show that with the increase of the amount of accelerator,the conductivity of the film increases first and then decreases.When the mass ratio of the accelerator to the epoxy resin(y)is 0.2,the maximum conductivity reaches 2.12×104 S·m-1.The power factor reached 1.33 mW·K-2·m-1,and the conductivity and power factor of the film increased by about 75%and 60%,respectively.In order to further optimize the electrical transport properties of thin films,so as to promote the application of thin films in the field of heat dissipation and refrigeration.The next work plan is to further optimize the performance of the large-size thermoelectric composite film by further optimizing the heat treatment temperature,pressure and time.