Preparation And Performance Of Perovskite Solar Cells Based On CsPbI₂Br

Since the perovskite solar cell was first reported in 2009,the current certification efficiency has exceeded 25.5%.Among them,the all-inorganic CsPbI₂Br perovskite,due to its suitable band gap and excellent thermal stability,is the most important part of the light-absorbing layer of solar cells.Promising candidate material.Carbon-based CsPbI₂Br devices have the advantage of low cost,but their photoelectric conversion efficiency is still lower than that of organic-inorganic hybrid devices and inorganic Cs Pb I₃ devices.Therefore,the preparation of CsPbI₂Br films with high crystallinity and low defect state density is a key issue at present.In this paper,a CsPbI₂Br perovskite layer with higher film coverage was prepared by preheating assisted spin coating process,and on this basis,the precursor solvent was adjusted to obtain a film with a larger grain size,and finally in the crystal lattice Doping with Cd²⁺reduces crystal defects and prepares carbon-based CsPbI₂Br perovskite solar cells with better performance.First,by controlling the volatilization of the solvent dimethyl sulfoxide（DMSO）,the CsPbI₂Br perovskite film was prepared by the direct spin coating method and the preheat assisted spin coating method respectively.The performance of the film and its devices have been tested and characterized.The research results show that the film coverage obtained by the preheating assisted spin coating method is relatively high.The average efficiency of the devices assembled with it is 8.97%,and the optimal efficiency is 9.13%.The device efficiency remains 43%of the initial efficiency when stored in the air for 30 days.Then,the preparation of the CsPbI₂Br perovskite film and the performance of the device were studied by adjusting the ratio of the precursor solvent.The results show that when DMF/DMSO=8:2（volume ratio）,the volatility and coordination strength of the mixed solvent reach an optimal balance,the crystallization nucleation rate induced by solvent evaporation is moderate,and the prepared CsPbI₂Br film is dense and without pinholes.The average efficiency of the devices assembled with it is 10.33%,the optimal efficiency is 10.44%,and the device efficiency remains 52%of the initial efficiency when stored in dry air for 30 days.Finally,by introducing cadmium iodide（CdI₂）into the CsPbI₂Br precursor,the preparation of the CsPbI₂Br perovskite film and its device performance were studied.The results show that 0.5%of Cd²⁺is doped into the CsPbI₂Br lattice,which partially replaces the Pb²⁺at the B site,effectively reducing the point defects caused by iodide ions and inhibiting ion migration.The average efficiency of the devices assembled with the Cs Pb_1-xCd_xI₂Br film is 11.91%,and the optimal efficiency is 12.18%.The device efficiency remains above 90%of the initial efficiency when stored in dry air for 30 days.