The Grain Growth Of CZTS Thin Film Solar By Monte Carlo Method And The Thermal Stress Simulation In The Annealing Process

Cu2ZnSnS4(CZTS)is a quaternary compound with a 1.45 eV band gap,which is very close to the optimμm band gap(1.5eV)required for semiconductor solar cells.The structure of this material is very close to the CIGS(copper indiμm galliμm selenide)thin film solar cells,which has chalcopyrite structure.Besides,CZTS has good photoelectric properties.The constituent elements are abundant on the earth,safe and non-toxic and environmentally friendly,and thus become one of the best candidate materials for the battery absorption layer.The preparation process of CZTS thin film solar cell was prepared by two-step deposition method.(1: CZTS precursor was prepared by electrochemical deposition;2: CZTS thin film was obtained by heat treatment and sulfuration)We have used the computer simulation method to reproduce the two-step preparation process to study the process of micro-scale grain growth during the preparation of the film and the factors which affect the thermal stress change during the annealing process.The aim of our research is to establish a feasible simulation method to study the micro-scale film growth process,in order to be able to guide the experiment.The research content mainly includes two parts:In the first part,the CZTS film morphology is represented by establishing a two-dimensional discrete model,and the process of grain growth is simulated by using the Monte Carlo method.At the same time,in the traditional Monte Carlo method,the algorithm of grain orientation change is improved,that is,the change of lattice orientation can only be selected in the orientation of the lattice point near eight positions.Through the improved algorithm,get a better simulation results.The simulation results show that the grain growth exponent is between 0.35 and 0.45,which is consistent with the experiment and simulation results of the domestic and foreign researchers,which verifies the feasibility of the simulation.In the second part,the stress of the CZTS thin film cell is simulated by the coupling calculation of velocity field,temperature field and solid field using ANSYS Workbench fluid-solid coupling module.The effects of these external parameters on the thermal stress of the films were investigated by changing the Mo layer,CZTS layer,the size of the substrate layer and the film annealing temperature.Finally,we can get the optimμm size of the CZTS thin film cell.