Research On Bifacial Perovskite/Silicon Tandem Solar Cells

At present,the preparation process of silicon solar cells has been very mature,and their efficiency records have basically reached the theoretical limit.The tandem solar cells made by combining silicon with different bandgap materials are a hot research spot to further enhance the efficiency,with the highest efficiency record of 47.6%,which has greatly exceeded the theoretical limit of silicon cells.In order to utilize the absorption spectrum more comprehensively,perovskite materials with a wide range of tunable bandgaps have become the best choice for top cells on tandem structures due to their low-cost preparation process and rapidly increasing efficiency records.The current tandem cells are single-sided cells.In order to further improve the performance of tandem cells,a bifacial two-terminal perovskite/silicon tandem solar cell is designed in this thesis.First,the physical model of the tandem solar cell is constructed,compared with the conventional two-terminal and four-terminal tandem cells,and the influence of the structural parameters on the performance is analyzed;then,the silicon and perovskite single-junction cells are fabricated separately;finally,the bifacial two-terminal tandem cell is fabricated and its process is optimized.The details of the work are as follows.（1）Modeling bifacial two-terminal tandem solar energy,analyzing the effects of the band gap and thickness of the perovskite absorber layer,silicon cell carrier lifetime,surface compounding rate and transport layer material properties on the cell performance,optimizing the cell structure parameters to achieve the best current matching through light modulation mechanism,comparing it with the conventional two-terminal and four-terminal tandem cells,and proving that bifacial illumination can effectively improve the cell performance.After optimization,the tandem cell has the V_{O C} of 1.646 V,the J_SC of20.07 m A/cm²,the FF of 86.07%,theηof 28.43%（2）The silicon and perovskite single junction cells were fabricated separately.The effects of diffusion source spin-coating speed and fleece-making reaction time on silicon cell performance were investigated,the silicon cell has the V_{O C} of 0.595 V,the J_SC of19.25 m A/cm²,the FF of 73.56%,theηof 8.42%;the effect of antisolvent drip addition time on the performance of the perovskite cell was investigated,the silicon cell has the V_{O C} of 0.93 V,the J_SC of 21.72 m A/cm²,the FF of 61.84%,theηof 12.52%.（3）Bifacial two-tandem perovskite/silicon tandem solar cells were fabricated.Using6 nm silver film as the intermediate composite layer and other steps as in the preparation of single-junction cells,a bifacial two-tandem tandem cell with an overall efficiency of9.49%was finally produced.