Synthesis At Room Temperature And Photoelectric Properties Research Of Bismuth Based Compound Films

Since 2009,lead halide perovskite thin film solar cells have developed rapidly.In recent years,in order to eliminate the potential risks caused by the heavy metal element lead,many researchers have begun to explore new lead-free perovskite materials that are environmentally friendly and have excellent photoelectric properties.Based on the replacement of the lead element in the lead halide perovskite thin film solar cells,this topic successfully prepared the bismuth based semiconductor pure inorganic perovskite materials CuBiI₄ and Cs₃Bi₂I₉based on the direct reaction of the elements at room temperature,and carried out the photoelectric performance system research.The results of the study indicate that bismuth,as an environmentally friendly element that can replace lead,has great potential for future photovoltaic applications.The specific research contents are as follows:1.CuBiI₄ ternary compound semiconductor film was prepared by copper powder,bismuth powder,and iodine powder as raw materials at room temperature?20°C-40°C?.X-ray diffraction?XRD?,X-ray photoelectron spectroscopy?XPS?and other analysis prove that the room temperature element reaction method can be used to prepare CuBiI₄ film without any impurities.Test results such as transient surface photovoltage?TSPV?and Hall effect indicate that CuBiI₄ is an N-type semiconductor material with good photoelectric performance.The photoelectric properties of films with different molar ratios of copper and bismuth were investigated,which showed that the concentration of photogenerated carriers increased significantly with the increase of the initial Cu/Bi molar ratio.Films with different molar ratios of Cu/Bi were applied to photodetectors,and the device performance was tested.The corresponding photoelectric responsivity of a specific photodetector initiated with 1:1initial molar ratio of copper to bismuth actually reaches 10⁶ times larger than that of the photodetector initiated with 0:1 initial molar ratio?pure Bi I₃?.It was assembled as a solar cell device as a light-absorbing layer,and a photoelectric conversion efficiency of 0.13%was obtained.2.The Cs₃Bi₂I₉ semiconductor thin film material was successfully prepared in the ordinary environment by the direct reaction method of room temperature elements,and the phase characterization was carried out by XRD,SEM,EDS,XPS and other test methods.TSPV,UV-Vis and other test results show that Cs₃Bi₂I₉ is a P-type semiconductor material with a forbidden band width of 2.0 e V,which is applied to the structure as a light-absorbing layer in the solar cell device of ITO/Sn O₂/Cs₃Bi₂I₉/Spiro-OMe TAD/Au,and its photoelectric conversion efficiency reaches 0.41%.The innovations in this article mainly include:?1?The equipment and operation required for the room temperature element reaction method are relatively simple,and the reaction conditions are mild,which overcomes the shortcomings of the previous preparation process that is complicated and energy-intensive,without the need for glove boxes and large magnetron sputtering equipment,With broad industrial application prospects.?2?Using Bi powder instead of traditional Bi I₃as the reaction raw material,it is easy to control the initial element molar ratio.Bi powder is more stable in the external environment,easy to store,and reduces production costs.?3?The addition of glacial acetic acid in the precursor solution can effectively restrain the disadvantage that Bi I₃ is easy to be oxidized and hydrolyzed in the external environment,so that the whole preparation process can be carried out in the external environment without the control of humidity and oxygen content,Our current approach of applying such element reaction at room temperature in ambient provides an universal synthetic strategy for preparing high quality Bi based perovskite-like photoelectrical materials.