Preparation And Thermoelectric Properties Of Stannous Sulfide Doped Thin Films By Electrodeposition

Thermoelectric materials can be made into an energy conversion device to reuse waste heat and convert it into electricity because of the Sebeck effect.SnS has orthogonal crystal structure similar to SnSe,so it should have excellent thermoelectric properties in preferential orientation similar to SnSe.By doping SnS with metal elements,the carrier concentration and resistivity of SnS structure are increased,and the thermoelectric properties are further improved on the basis of SnS texture.Sn S was obtained by potentiostatic electrodeposition.In this paper,the electrodeposition parameters and bath conditions in the preparation process were explored.SnS with different texture was prepared by adding additives.SnS thin films with different metal doping amount were prepared by adding metal salts into the electrodeposition process.The effects of doped metal on the thermoelectric properties of SnS thin films were compared.Further optimizing the preferred orientation of doped SnS films.The thermoelectric properties of SnS thin films with metal doping and texture were further analyzed.The main achievements are as follows:(1)(1)p-SnS thin films were prepared under optimized electrodeposition conditions.The structure of SnS film is controllable after optimization.By using additives cetyltrimethylamonium bromide(CTAB)and urea to make SnS grow preferentially in(200)and(040)directions,respectively.(200)-SnS films with T(200)=2.32 were obtained.(040)-SnS films with T(200)=2.73 were obtained.Finally,the texture in(200)direction has the lowest resistivity,which is 54%of SnS.The reason is that the preferred orientation in(200)direction reduces carrier scattering and improves mobility.(2)The resistivity of SnS films is further reduced by doping metallic elements in SnS films.Al-doped SnS thin films were prepared by electrodeposition,and p-type Al-doped SnS thin films were obtained.Cu-doped SnS thin films were prepared by electrodeposition.The doping content can be controlled without changing the phase structure of SnS films.Among the doped films,the lowest resistivity measured by 0.5?1.0%Cu-SnS is 26%of SnS.Although the mobility decreases slightly,the main reason is that the carrier concentration increases greatly.The acceptance electron of Cu in Cu-SnS increases the hole in SnS film,provides the acceptor level,reduces the bandgap of SnS,and finally increases the carrier concentration.(3)On the basis of doping SnS thin films,the control of textures of doped-SnS is realized.By using CTAB and urea to promote the preferential growth of Al-SnS in(200)and(040)directions respectively,the preferential orientation films of(200)-Al-SnS with T(200)-4.53 and(040)-Al-SnS with T(040)=5.76 were obtained.By using CTAB and urea to promote the preferential growth of Cu-SnS in(200)and(040)directions respectively,the preferential orientation films of(200)-Cu-SnS with T(200)=3.93 and(040)-Cu-SnS with T(040)=3.85 were obtained.Finally,the lowest resistivity is(200)-Cu-SnS film,which is 7.6%of SnS.Although the mobility decreases slightly,the main reason is that the carrier concentration increases 102 times.T he carrier scattering and band gap of SnS are reduced,the carrier concentration is increased and the resistivity is reduced.