Research On Preparation And Performance Of All-inorganic Perovskite Solar Cells Based On CsPbI_3-xBr_x

In recent years,in response to the energy crisis and environmental pollution,the solar photovoltaic industry has developed rapidly.Among them,the perovskite solar cell has won the favor of researchers due to its excellent photoelectric performance and low preparation cost,and has developed rapidly as the third-generation solar cell in the past ten years.Although the photoelectric conversion efficiency of the organic-inorganic hybrid perovskite solar cell is already very high,its stability problem still exists,which limits its practical progress.As an alternative to organic-inorganic hybrid perovskite solar cells,all-inorganic perovskite solar cells have gained widespread attention due to their excellent environmental stability.Based on the all-inorganic perovskite solar cell,this thesis designs a planar perovskite solar cell device with Cs Pb I_3-xBr_xas the main material,optimizes the perovskite material and device structure,and proposes an improvement method for stability.The main work of this paper is divided into the following three parts:1.The CsPbI_3-xBr_xperovskite film is prepared by a simple one-step method,and the photoelectric properties of the material are changed by adjusting the ratio of Br doping.The experimental results show that the X=1.2 component exhibits the best photoelectric conversion efficiency.The visible light absorption spectr?m of this material is blue-shifted compared to the X=1 component material.Although the absorbed light wavelength becomes smaller in the visible light range,due to The blue light energy is relatively high and the relative total absorbed energy loss is small.Our analysis is because its valence band top energy level and the hole transport layer's valence band top energy level form a good match,which strengthens the hole transport ability,and thus obtains Higher short-circuit current and smaller series resistance.The performance parameters of the optimal device prepared from this material are:short-circuit current 14.83 m A·cm^-2;open-circuit voltage 1.2V;fill factor FF=64.98%;photoelectric conversion efficiency 11.60%.Since the tolerance factor t of the perovskite material when X=1.2 is close to 1,the unit cell structure is closer to the cubic crystal phase,and it is more difficult for phase change to occur.In the stability test,the X=1.2 component performed very well,and it showed more than 90%tolerance in h?midity stability,long-term stability and light stability,which was better than the X=1 component..2.Based on the previously obtained CsPbI_3-xBr_xperovskite with X=1.2 composition,the influence of the conductive device substrate and the electron transport layer on the device was further studied.Four different device substrate structures were designed,and a series of characterization and photoelectric performance tests were performed.It was found that the ITO/Sn O₂structure has the best electron transmission efficiency and the lowest series resistance.It is found from the photol?minescence spectr?m that the ITO/Sn O₂structure has the lowest l?minescence peak,indicating that its electron transmission ability is the strongest,and the reflection and absorption spectra of the material show that the structure has good light transmittance.Both the J-V curve and the complex impedance test after the battery are prepared show that the structure has lower resistance and is more suitable for use as the substrate of the device.After that,we optimized the preparation method of the light-absorbing layer,and controlled the thickness of the perovskite light-absorbing layer by adjusting the concentration of the precursor solution and the spin coating speed.Due to the limited carrier transport distance,a suitable light-absorbing layer thickness can produce a larger open circuit voltage.The experimental results show that the most suitable thickness can be achieved when the current driver solution concentration is 1.2mol/L and the spin coating speed is 4000rpm/min.The photoelectric parameters of the perovskite device prepared by this method are:short-circuit current 15.79 m A·cm^-2,open-circuit voltage 1.19V,fill factor FF=69.20%,achieving a photoelectric conversion efficiency of 13.03%.3.A CsPbI_3-xBr_xperovskite solar cell with an anode structure mainly composed of conductive graphite is designed.Instead of the Sprio-OMe TAD hole transport material with poor stability and heat resistance,based on the materials and preparation methods presented above,the carbon electrode is prepared by scraping conductive carbon paste,and the carbon electrode is used as a highly stable hole The transport layer and anode are used in solar cells.Adhesive tape is used to limit and control the height of the layer,and realize the preparation of low-cost large-area(1cm²)perovskite solar cells.The final photoelectric parameters of the device are:short-circuit current 12.29 m A·cm^-2,open-circuit voltage 1.06V,fill factor FF=60.04%,photoelectric conversion efficiency reaches 7.85%Solar cell devices based on carbon electrodes exhibit excellent stability.The high temperature resistance of graphite improves the stable working ability of the device in high temperature environments.At the same time,the hydrophobicity of the carbon material also improves the h?midity stability of the device.Compared with Sprio-OMe TAD hole transport material,although the series resistance increases and the photoelectric conversion efficiency decreases,the carbon electrode prepared by this method has lower difficulty,low cost,and improved device stability,and can be promoted as an excellent alternative material.