Surface Passivation Treatment Of Antimony Sulfide Thin Films And Their Photoelectric Performance

As a green and inexhaustible renewable energy,photovoltaic power generation has developed rapidly in recent decades.Among many photovoltaic materials,metal chalcogenide semiconductor compounds have been widely concerned.Sb₂S₃material has attracted wide attentions in the field of photovoltaic due to its excellent photoelectric performance,good stability,low cost,and the diversity of preparation methods.At present,the preparation methods of Sb₂S₃thin films mainly include chemical bath deposition,thermal evaporation,atomic deposition,and solution method.Among them,the solution method has become a popular preparation method for Sb₂S₃thin films owing to its convenience.However,due to the use of organic solvents in the process of preparing precursors,some organic impurities will inevitably be introduced into the Sb₂S₃thin films.In addition,during the annealing process,due to the evaporation of the solvent,there are a large number of penetrating holes in the Sb₂S₃thin films.Moreover,after annealing,massive sulfur vacancy defect will exist in the Sb₂S₃thin films.And meanwhile,some amorphous Sb₂S₃may not be completely converted into Sb₂S₃crystals.There issues have severely hindered the improvement of Sb₂S₃-based photoelectric devices.In order to solve these issues,researchers have adopted many strategies to improve the quality of Sb₂S₃thin films,mainly including additive engineering,surface/interface treatment and selenization.Among them,the surface/interface treatment is the most commonly used method for the fabrication of planar Sb₂S₃solar cells thanks to its simpleness and effectiveness.Based on this,in this paper,Sb₂S₃thin films are prepared using the solution method,and the surface of Sb₂S₃thin films is passivated by 3-mercaptopropionic acid（MPA）and polymethyl methacrylate（PMMA）to optimize the photoelectric performance of Sb₂S₃devices.The main research contents are as follows:（1）Sb₂S₃thin films are prepared by the solution method.The Sb₂S₃precursor solvent,precursor solution concentration and annealing temperature are optimized by X-ray diffraction（XRD）and scanning electron microscopy（SEM）.Finally,smooth,dense and flat Sb₂S₃films are prepared.（2）3-Mercaptopropionic acid（MPA）is used as the sulfur source to sulfurize the surface of Sb₂S₃thin films,and the sulfurization mechanism of Sb₂S₃thin films by MPA is investigated.The results show that MPA can interact with the Sb₂S₃thin films,sulfurize the impurity phase on the surface,and passivate the sulfur vacancies on the surface of Sb₂S₃thin films,thereby improving the photoelectric performance of Sb₂S₃devices.Compared with the device without MPA treatment,the defect state density of the Sb₂S₃optoelectronic device treated with MPA is significantly reduced,and the photoelectric response current is 60 times that of the control device.（3）Polymethyl methacrylate（PMMA）is used as an ultra-thin passivation layer to passivate the surface of Sb₂S₃thin films,and the passivation mechanism of PMMA is investigated.The results show that PMMA can effectively fill the penetrating pores in the Sb₂S₃thin films,so dense and smooth Sb₂S₃thin films can be obtained.In addition,PMMA can interact with Sb³⁺and S^2-in the Sb₂S₃thin films,effectively passivating surface defects.Compared with the control device without PMMA passivation,the photoelectric response current of the passivated device is100 times that of the control device.