Research On Antimony-based Chalcogenide Thin Film Solar Cells

To develop renewable energy technology is an important way to solve current energy and environmental issues.Due to the wide distribution,non-pollution and inexhaustible feature,solar energy is considered to be one of the most promising renewable energies.Thin film solar cells which can convert solar energy directly into electric energy are the most efficient devices for solar energy utilization.Currently,the developed thin film solar cells absorber materials include silicon,CdTe,Cu?In,Ga?Se2,etc.,all of these have achieved excellent photovoltaic performances.However,there are still several insurmountable shortcomings,such as high energy consumption,containing high toxicity or rare elements.Therefore,researchers are still searching novel semiconductor absorber materials to meet the requirements of low processing temperature,low toxicity,earth abundance,and high device efficiency.Sb-based chalcogenide semiconductors meet the above requirements and achieves rapid development.This dissertation focuses on the preparation of Sb-based chalcogenide?Sb₂S₃ and CuSbS2?and their application in solar cells.Sensitized solar cells structure is the most common structure for Sb₂S₃ solar cells.The high specific surface area of TiO₂ mesoporous films is beneficial to achieving high loading amount of Sb₂S₃ and fully absorbing incident light.However,a large number of interfaces are generated,resulting in serious interfacial charge recombination,which is detrimental to open-circuit voltage of the devices.To suppress the interfacial recombination an ultrathin SiO₂ blocking layer was deposited on the surface of the mesoporous TiO₂ film using a room temperature chemical bath method.We found that the SiO₂ blocking layer has a significant impact on the morphology of Sb₂S₃.SiO₂ layer increases the specific surface area of the mesoporous film,thus provides more sites for the deposition of Sb₂S₃,and increase the deposition amount of Sb₂S₃.Electrochemical impedance spectroscopy indicate that the addition of SiO₂ layer improves the recombination resistance at TiO₂/Sb₂S₃/P3HT interfaces.The open-circuit voltage-decay curves indicate that the attenuation rate of open-circuit voltage decreases after the addition of SiO₂ layer,these indicate that the SiO₂ layer effectively suppresses the charge recombination of TiO₂/Sb₂S₃/P3HT interfeces.The SiO₂ blocking layer significantly increases the open-circuit voltage and fill factor of Sb₂S₃ sensitized solar cells,the device efficiency increases from 3.00%to 3.96%.Sb₂S₃ sensitizer prepared by traditional low temperature chemical bath deposition method contains a variety of unavoidable impurities,which will act as the recombination centers and thus reduce device performance.To overcome this problem,a cation exchange method was developed to deposit Sb₂S₃ sensitizer.This method requires low temperature,short operation time and is suitable for large area depositioa We deposited a conformal ZnS coating on the mesoporous TiO₂ film,and then dipped the film into Sb source solution for several minutes to obtain amorphous Sb₂S₃.The cation exchange reaction was accopanied by the dissolution of ZnS,so the Sb₂S₃ sensitizer did not maintain the morphology of ZnS conformal coating.The Sb₂S₃ sensitizer prepared by this method has the characteristics of phase pury,Sb-contained impurities-free and S deficient.The optimized Sb₂S₃ sensitized solar cell obtained a power conversion efficiency of 3.69%,which was higher than the devices made by chemical bath method.In addition,cationic exchange has potential application in controllable synthesis of Sb₂S₃ nanomaterials.For Sb-based chalcogenide novel materials,we prepared three kind of Cu-Sb-S polycrystalline films by a simple solution-processed method.This method is based on the pyrolysis of organic metal precursor molecules,which are prepared by reaction of butyldithiocarbamic acid with Cu2O and Sb2O3.The Cu/Sb ratio in the precursor solution determines the phase of the resulted film.When the Cu/Sb ratio is 1,the product is CuSbS2.Pyrolysis temperature has a significant effect on the film crystallinity and morphology,when annealing temperature is 340 ?,smooth and dense CuSbS2 polycrystalline film with high crystallinity can be obtained.CuSbS2 planar heterojunction solar cells of FTO/CdS/CuSbS2/Au structure were assembled achieving a power conversion efficiency of 0.68%under one sun illumination.