The Research On Properties And Preparation Of SnSe Thermoelectric Thin Film Materials

Thermoelectric materials with superior performance can directly convert heat into electrical energy.It is a kind of environmentally friendly materials being widely applied in the future.Tin selenide?SnSe?is a narrow bandgap and p-typed semiconductor material in IV–VI,the direct band gap is about 1.3eV and the indirect band gap size is about 0.9eV,it is a potential and new material of the absorption layer applied to thin film solar cell,its rate is extremely high.Recently,it has been paid much attention by researchers all over the world.According to the research problem in current about SnSe semiconductor,this paper have a research on the thin film preparation and doping modification of main characteristics on SnSe semiconductor.With the different doping composition and preparation conditions,we want to find the differences of the SnSe thermoelectric Thin films to find the optimum preparation conditions and doping parameters.The last task is to analyze the data of the test samples according to the thermoelectric theory.The research results of this paper have important reference to the exploration and development of new thermoelectric thin films.The main contents of this paper are as follows:?1?By using thermal evaporation method,SnSe thin film thermoelectric materials with different thickness are prepared.The thermoelectric properties are tested and analysed,the best thermoelectric properties of thin film thickness parameters are founded.The experiment shows when the thickness is about 60nm,under the condition of high and low temperature gradient of 38.4K,the sample maximum open circuit thermoelectric power can reach 600mV.?2?SnSe composite thermoelectric films with different Ag doping ratios are prepared respectively.Its thermoelectric properties are analyzed.The experimental result shows the SnSe composite thermoelectric material is constructed by putting Ag into the SnSe.Using the electronic Ag donor supply capability,the number of electrons inside the composite thermoelectric material is greatly increased,conductivity of the SnSe composite thermoelectric material is greatly enhanced.The result shows the conductivity of SnSe composite thermoelectric material doped with Ag ratio of 45%is increased from 14Sm-1 to 21Sm-1;In the case of the temperature gradient of 38.4K,the maximum open circuit electromotive force of the SnSe composite thermoelectric material doped with Ag ratio of 45%is up to 1400mV,which is 2.4 times higher than that of the undoped sample.?3?In order to compare the influence of different metal doping elements on thermoelectric properties of SnSe,the SnSe composite thermoelectric thin films with different Cu doping ratios are prepared.The crystal structure,surface morphology and thermoelectric properties of the samples are analyzed.The test shows the doping of Cu,compared to SnSe composite thermoelectric materials,SnSe composite thermoelectric materials as the same doping ratio has higher electrical conductivity and Seebeck coefficient.The conductivity ratio of SnSe doped Cu composite thermoelectric materials of the 45%samples increased from21Sm^-1 to 29Sm^-1 before being doped Ag.The thermoelectric parameters are significantly higher than those of the two thermoelectric materials.