Investigations On The Electrodeposition Process And Preparation Technology Of Cu-Se Thermoelectric Films

In recent years,with the increasing awareness of enviremntal protection,the research and development on preparation of thermoleectroic material and the assembly of thermoelectronic appliance have drawn a wide range of attention.The outstanding thermoelectronic performance of p-type Cu₂-xSe material in mid-temperature range has gradually made itself being in a hot research.In this dissertation,with the purpose of preparing high-performance p-type Cu₂-xSe thin film material,a series of experiments realted to electrochemical deposition method have been conducted systematically.The reduction behavior of Cu-Se compound electrodepostion in sulfuric acid solution was analysed by cyclic voltammetry?CV?linear sweep voltammetry?LSV?and electrochemical impedance spectroscopy?EIS?.Based on that,an intense research on the preparation technology of electrodeposition process preparing p-type Cu₂-xSe thin film materials was carried out,using EDS,SEM and laboratory homemade Seebeck tester and Resistivity tester to analyze the effect of the parameters of electrodepostion on morphology,composition and thermoelectric properties of p-type Cu₂-xSe material prepared by electrodeposition.Solution temperature,pH value of solution and depostion potential were taken into consideration and the optimized preparation technology was obtained.The results show that in Cu unitary system,CuII has a two-step inreverable reduction reaction,the Cu₂+ was reducted to Cu+ then to Cu0,while in the SeIV system,there is a three-step inreverable reduction reaction taking place.The deposition potentials of CuII and SeIV are similar when the pH value was 2.A relative high pH value and a more positive deposition potential leads to the compact and smooth surface morphology of the samples.A more negative deposition potential and a relative high pH value makes the protion of Cu in the samples higher.The optimal techonology was obtianed: solution comprised of 48 mM CuSO4·5H2O,2mM H2SeO3,pH value 2,temperature 40?,and the electrodeposting potential of 0.04 V.The Seebeck coifficent of p-type Cu₂-xSe thin film with the best thermoelectric properities is 56.0mV/K,the coreesponding power factor is 0.13 mW/?K²m?.