Research On The Fabrication Of CZTSe Films By Co-evaporation Method For Solar Cells

Solar cells are devices that use sunlight to produce electrical energy.In recent years,with the rapid development of solar energy technology and the continuous expansion of industrial production,the solar cell industry has developed rapidly.The manufacturing cost of solar cells has rapidly declined due to the rapid development of thin-film solar cells.Copper indium gallium selenide Cu(InGa)Se2(CIGS)is a widely used commercial thin-film solar cell material,but due to its high cost and toxicity,gallium indium has limited its large-scale application.People have developed similar performance copper zinc selenium Cu2ZnSnSe4(CZTSe)materials.The composition and crystal structure of the CZTSe film material have a great influence on the application of the material.In the co-evaporation process,the content of copper is high,the crystal structure is perfect,the carrier density is high,and the copper content is too high,which can lead to the failure of the battery;when the tin evaporation temperature is low,CZTSe is easily decomposed;when the zinc evaporation temperature is high,the material forms a filter Zinc and selenium compounds will reduce the short-circuit current density.This article studied in detail the co-evaporation process of CZTSe film materials,and obtained good performance CZTSe thin-film battery materials.And its structure composition and electrochemical performance were studied and analyzed.The main contents and results are as follows:1)The Cu content can affect the crystal quality of the CZTSe film to some extent.When the content of CuWhen too high or too low,the CZTSe film becomes N-type.2)The evaporation temperature of zinc is lower than that of other metals.When the evaporation temperature is too high,the current density of the battery will be reduced,causing the battery to fail when the amount of copper is excessive.This is because the band gap of ZnSe is relatively wider than that of CZTSe,and ZnSe at grain boundaries may act as a barrier,thereby reducing grain boundary boundary recombination and increasing the open circuit voltage.The presence of ZnSe on the surface and on the back side may impede the collection of carriers,thereby reducing the short-circuit current density and fill factor.3)Selenium evaporation temperature is low,which will lead to reduced selenium content in the material.When the evaporation temperature of selenium rises to 230°C,the content of Sn in the thin film changes little or does not change,and the evaporation temperature of selenium increases again,and Se raw material will be wasted.4)The effect of CuxSey on the growth of CZTSe thin films is relatively small compared to the effect on CIGS,which may be related to the difference in grain boundary Cu distribution caused by the Fermi level near the boundary of the CZTSe thin film,which makes the CZTSe and The growth mechanism of CIGS is not exactly the same.The substrate is soda-lime glass sheet,Double-layer Mo back contact and the intrinc ZnO prepared by magnetron sputtering menthod.CZTSe absorber with good crystallization and Ni-Al electrodes were prepared by evporation process.CdS buffer layer which is relatively homogeneous was prepared by CBD.Finally,an optimal efficiency of 1.99% for CZTSe solar cells was achieved.