Preparation And Optimization Process Of Cu₂znSnS₄ Hole Transport Layer And Perovskite Layer

This paper mainly studies the synthesis of Cu₂ZnSnS₄,a novel hole transport material,and its application in perovskite cells.Alkaline metal ion doping is carried out on the basis of the traditional perovskite cell preparation process to optimize the crystallization performance and film forming property of the photovoltaic active layer,thereby improving its photoelectric conversion performance.In response to the above research,the following conclusions were drawn:The Cu₂ZnSnS₄ nanoparticles are synthesized by thermal injection process with a particle size of approximately 25 nm.The hole transporting material of perovskite cell was prepared by spin coating process.By comparing the film forming properties of Cu₂ZnSnS₄ nanoparticles in different dispersants and different concentrations,it was found that the preparation of Cu₂ZnSnS₄ based on spin coating process a suitable dispersing agent for the transport layer is hexyl mercaptan and a suitable concentration is 200 mg/mL,and the highest efficiency of the cell device prepared by the spin coating process is 4.15%.At the same time,the hole transport layer was prepared by manual spraying process,and the density of the hole transport layer film was further improved,and the highest efficiency of the obtained cell device was5.73%.Based on the low-cost"one-step"spin coating process,the perovskite precursor solution is doped with alkaline metal potassium ions.Potassium ions are mainly located in the lattice gap of the perovskite crystal structure due to the small ionic radius.At the same time,potassium ions can act as heterogeneous nucleation cores to promote the formation of perovskite grains.By doping an appropriate amount of potassium ions,the perovskite grain size becomes larger,the hysteresis effect of the device is greatly reduced,and the device stability is improved.The short-circuit current density of the device was increased from the initial value of 14.73 mA/cm² to19.98 mA/cm²,and the device efficiency value was increased from 10.16%to13.57%.Doping magnesium iodide in the perovskite precursor solution,and preparing the magnesium ion doped perovskite photovoltaic active layer by"one-step"spin coating process.The magnesium ion and the lead ion are divalent ions,and the magnesium ion partially replaces the lead ion in the perovskite structure,so that the interplanar spacing of the perovskite becomes larger.The doping of magnesium ions increases the grain size of the photovoltaic active layer and improves film formation.After doping,the band gap value of the photovoltaic active layer becomes larger,and the open circuit voltage of the obtained device increases and the short circuit current value increases.The investigation found that the proper doping concentration is 1 mol%,the maximum efficiency of the device is 15.25%,and the open circuit voltage can reach1.01V.