Preparation And Photoelectric Characterization Of CZTSSe Absorption Layer Based On Thiol-organic Amine Syetem

The kesterite structure of CZTSSe semiconductor material has attracted the attention of researchers at home and abroad due to its earth abundant elements,low toxicity and environmental,adjustable optical band gap?1.0¹.5 eV?and high light absorption coefficient(>10⁴ cm^-1).At present,the certified highest efficiency of CZTSSe thin-film solar cell is 12.6%which was based on the hydrazine-based solution approach.An important factor limiting the further development of this system is that hydrazine is a highly toxic substance,which is not only harmful to human body but also to the environment.In this paper,we prepare the CZTSSe absorption layer film with low toxicity thiol-organic amine solution system.We mainly study the optimum conditions for selenization of CZTSSe film and the effect of rare earth element La doping on the photoelectric properties of CZTSSe absorption layer.The details are as follows:1.A mixture of ethanolamine,thioglycolic acid and ethylene glycol methyl ether was used to dissolve CuO,ZnCl₂ and SnCl₂ to prepare CZTS precursor solution.The CZTS preset film was obtained through seven cycles of spin coating and low-temperature sintering,and the CZTSSe film was further obtained by high-temperature selenization.Experimental conclusion was as follows:The film was prepared under the condition that selenide temperature is 540?and selenide time was 10 min and it has pure phase,the best degree of crystallization,the most compact and uniform surface grains,and the optical band gap value of the film is close to1.2eV.We introduced Se source to the CZTS precursor solution in order to promote the growth of the fine granular layer of the film.Five groups of CZTSSe films were prepared by dissolving different amounts Se in CZTS precursor solution.The experimental conclusion is as follows:after testing the XRD patterns of five groups of thin film samples,it is found that the diffraction peak along the crystal direction?112?of the thin film has a small angle deviation with the increase of the amount of Se and it was proved Se effectively entered the lattice.Through the characterization analysis of SEM,the introduction of Se into thin film by this method can indeed promote the growth of grain,making the size of thin film grain more uniform and promoting the growth of the fine granular layer of the film.2.The CZTSSe absorption layer film prepared by the rare earth element La doping was characterized by XRD and Raman.It was found that when the doping amount of La element was 0.10 mmol,the film prepared has no impurity phase and the peak intensity of diffraction peak was the sharpest,and the degree of crystallization was the best.The optical band gap doped thin film had a width change of 0.1⁰.2 eV.Through the I-V test of the film,it was found that the conductivity of the film prepared with the addition of the nitrate of the rare earth element La had a good improvement.Moreover,when the doping amount was 0.10 mmol,the I-V curve test showed that the conductivity reaches the highest.