Fabrication Of High-efficiency Tin-based Perovskite Solar Cells And Therotical Research On All-perovskite Tandem Solar Cells

In recent years,the power conversion efficiency of lead-based perovskite solar cells has exceeded 26%,becoming the leader in the third-generation of thin-film solar cells.However,almost all of the currently reported high-efficiency perovskite solar cells are based on lead-containing perovskite.Due to the biocompatibility of lead,the commercialization process of perovskite solar cells may be hindered.Therefore,seeking high-efficiency non-lead materials has become an important direction in the field.Tin is considered to be one of the most potential substitute materials for lead due to its similarity in the nuclear electronic structure and photoelectric properties,which is located in the same main group as lead.Based on this,this paper achieved a power conversion efficiency of 11.5%for tin-based perovskite solar cell through additive engineering.Besides,we also conducted preliminary exploration and theoretical research on all-perovskite tandem solar cells.The main research contents are as follows:1)High-efficiency tin-based perovskite solar cells were prepared.By doping o-phenylenediamine hydrochloride（o-PEHCl）as an additive in the organic/inorganic perovskite absorption layer,a strong hydrogen bond interaction is formed between the amino group（-NH₂）in the o-phenylenediamine hydrochloride and the uncoordinated iodine ion（I^-）on the perovskite surface.It effectively inhibits the oxidation of Sn²⁺,thereby reducing the defect state density,improving the film quality,and enhancing the stability of device.The research results show that the crystal orientation and crystallinity of perovskite thin films with o-PEHCl addictive improved,and the photoluminescence and ultraviolet-visible light absorption intensity have significantly increased.The o-PEHCl additive is conducive to the formation of hydrogen bonds,can passivate defects in the films and convert Sn⁴⁺to Sn²⁺.It makes the films more uniform and dense,enhancing the carrier transport ability,reducing the density of defect states,and reducing charge recombination losses.The experimental results show that the device doped with 3%o-PEHCl achieves the best efficiency of 11.50%and has better device stability.2)Based on tin-based high-efficiency devices,the exploration of lead-free all perovskite series solar cells were carried out.Firstly,the Shockley Quessel（SQ）theory is modified to obtain a theoretical limit efficiency,which considers non-radiative recombination to closing conditions.Next,the absorption layer of sub-cells uses perovskite materials with a wide band gap（～1.79 e V）and a narrow band gap（～1.11 e V）,and current matching by adjusting the thickness of the calcium titanium layer of the two sub-cells.In addition,considering different application scenarios of the device,the effect of operating temperature on device performance was simulated.Besides,the influence of carrier recombination at the absorption layer and interface.Finally,a simulation test is conductes on the optimized all-perovskite series solar cell.The results showed that the open circuit voltage was 1.72 V,the short circuit current density was 18.51 m A/cm²,the filling factor was 86.5%,and the device conversion efficiency was 27.54%.This work provides an effective strategy for the fabrication of tin-based perovskite solar cells and provides some theoretical guidance for non-lead all perovskite series solar cells.