Properties Of Bi₂Se₃ And SnS Thin Film Devices

In the research of dye-sensitized solar cells,the cost of metal platinum Pt is relatively high.It is an urgent problem to study the counter-electrode material instead of metal platinum.In this paper,three growth temperatures of film materials,390℃,430℃,and470℃,were successfully prepared on conductive glass by molecular beam epitaxy.The diffraction peaks of Bi₂Se₃ were detected by X-ray diffraction technology.Scanning electron microscopy（SEM）results showed that the film at 470℃exhibited a larger specific surface area due to its more vertical substrate growth structure.The short-circuit current density is 11.22 mA·cm^-2,the open-circuit voltage is 0.675 V,the filling factor is 57.43%,and the photoelectric conversion efficiency is 4.35%close to the Pt electrode.With the increase of the specific surface area of the electrode material,more I^-/I₃^-ions in the electrolyte are transferred,which effectively improves the photoelectric conversion efficiency.Counter electrodes of hollow microspheres SnS,reduced graphene oxide RGO and hollow microspheres SnS@RGO were successfully prepared on FTO by one-step hydrothermal method.Firstly,the characteristic peaks of SnS and RGO coincide well with those of standard cards in X-ray diffraction measurements,but the diffraction peaks of graphene in SnS@RGO composites are lower,indicating that SnS has been wound and covered by graphene.Secondly,the hollow structure of SnS was observed by scanning electron microscopy（SEM）and transmission electron microscopy（TEM）,and the results of specific surface area test showed that the hollow microspheres SnS@RGO had higher specific surface area.Finally,in the electrochemical performance test results,the series resistance of SnS@RGO is 6.7Ω,the charge transfer resistance is 0.17Ω,the exchange current density is 0.6 mA·cm^-2,the diffusion current density is 1.63 mA·cm^-2.The short circuit current density of SnS@RGO hollow microspheres is 18.90 mA·cm^-2,the open circuit voltage is 0.705 V,the filling factor is57.91%,and 8.21%.Photoelectric conversion efficiency.Compared with the traditional platinum electrode,the photoelectric conversion efficiency of 7.75%is obviously higher,and the production cost is lower,the process is simple,and the performance is stable,which can better replace the noble metal platinum electrode.