Preparation And Research Of Copper-Indium-Gallium-Selenium Solar Cells By Non-Vacuum Method

With the exploitation and utilization of traditional energy sources,a large amount of non-renewable resources has been consumed which leads to the scarce resources on the earth,so people begin to focus on the sustainable development energy.Asasecond-generationthin-filmsolarcell,Copper-Indium-Gallium-Selenium（CIGS）solar cells have the advantages of high light absorption,no photodegradation,direct band-gap of the absorption layer,which can meet the needs of industry and daily life.Besides,the absorption layer of CIGS solar cells only needs the micron level to generate photovoltaic power.The thickness of the entire solar cell is less than 1 mm,and it can be applied to extensive flexible surfaces.The flexible CIGS solar cell is suitable for all kinds of special landforms.However,there are still some problems in the development of CIGS solar cells,such as the preparation process of the entire vacuum,the difficulty in controlling complex element ratios and high production costs.To solve the above problems,this thesis used a simple non-vacuum process to prepare a CIGS absorption layer and assembled it into a solar cell.The main work was as follows.1. Preparation of CIGS solar cells by liquid phase methodIn this paper,Copper chloride,Gallium chloride and Indium sulfate were dissolved in the 2-methoxyethanol as a metal-salt,triethanolamine was used as a complex reducing agent,and selenium dioxide was used as a selenium source.CIGS precursors prepared by the solution method were annealed.The CIGS absorbing layer film was obtained after the heat-treatment.The single-factor experiment was used to optimize the CIGS thin film.The simple CIGS solar cells were assembled to measure the photovoltaic conversion efficiency.The optimal concentration and conditions were 3.0 mmol·L^-1Gallium chloride,5.0 mmol·L^-1Copper chloride,3.5 mmol·L^-1Indium sulfates,20 mmol·L^-1Selenium dioxide,300μL·L^-1triethanolamine and the annealing temperature of 500℃.The formation mechanism of the CIGS absorption layer was analyzed by electrochemistry tests and characterization.2. Ink method to prepare flexible CIGS absorbing layerThe CIGS crystals were prepared by Non-vacuum method and further processed by ball milling to obtain CIGS powders.In this process,N-methylpyrrolidone and N,N-methyl methacrylate were used as solvents,and polyvinylidene fluoride was as a binder to prepare CIGS inks.CIGS absorption layers were coated on the different rigid and flexible substrates（FTO conductive glass,ITO conductive glass,aluminum foil and PI film）to assemble into different CIGS solar cells on the different electrode.The CIGS materials prepared by two different non-vacuum methods were characterized.XRD was used to characterize the crystal structure of CIGS powder and film,XPS was carried out to analyze the element valence state of CIGS powder,and the surface morphology of CIGS powder and thin films were analyzed by SEM and TEM.The optical properties of CIGS films were studied by UV-vis,the carrier concentration of CIGS films was measured by M-S,and the basic performance of assembled CIGS solar cells was performed by LSV test.The results indicated that the CIGS thin film prepared by solution method had a band gap of 1.54 e V and a carrier concentration of 8.98×10¹⁴cm^-3.After assembling into CIGS solar cell,its open circuit voltage was 0.59 V,the short-circuit current density was 0.53 m A·cm^-2,the FF value was 43.80%and the photoelectric conversion efficiency was 0.14%.The CIGS film prepared by the ink method had a band gap of 1.45 e V and a carrier concentration of 6.81×10¹⁵cm^-3.After assembling into CIGS solar cell with different substrates,the flexible PI film substrate was the best with an open-circuit voltage of 0.51 V.Besides,the FTO conductive glass as the substrate had a maximum short-circuit current density of 0.91 m A·cm^-2,the FF value was 24.76%and the photoelectric conversion efficiency was 0.078%.