Research On Semitranslucent And Flexible Solar Cells Based On CsPbIBr₂ Perovskite

Perovskite solar cells appeared for the first time in 2009 and have developed rapidly in recent years.At present,the photoelectric conversion efficiency（PCE）of organic-inorganic hybrid perovskite solar cells has reached 25.5%.In the past years,the inorganic perovskite solar cells have been widely studied due to excellent light and thermal stability.Among them,CsPbIBr₂ material has a suitable band gap of 2.05 e V and good phase stability,is one of the promising light absorption layer materials.Although the photoelectric conversion efficiency of CsPbIBr₂ is still lower than the organic-inorganic hybrid perovskite,its larger band gap has advantages in applications such as visible semitranslucent devices.In this paper,all-inorganic visible semitranslucent perovskite solar cells are successfully prepared by optimizing CsPbIBr₂ perovskite film annealing process,doping amounts of Rb I,using NiO_X as a hole transport layer and ITO as a top electrode.In addition,the low-temperature annealing process of perovskite film is achieved by precursor solvent engineering and visible semitranslucent flexible perovskite solar cells based on all-inorganic CsPbIBr₂ are prepared.The main research contents and results of the paper are as follows:（1）CsPbIBr₂ film annealing process optimization and cell performance.Based on the one-step solution method,the influence of annealing process on perovskite film and device performance is studied.First,the CsPbIBr₂ film and device prepared by one-step annealing method and two-step annealing method are compared.As a result,it is found that the two-step annealing method facilitates the nucleation crystallization of the perovskite film,improves the quality of the film and performance of the device,then the cell efficiency produced is 7.33%.On this basis,the initial annealing temperature in the two-step annealing method is further optimized,and 120°C is the optimum annealing temperature after gradient experiment.The perovskite grains prepared under this annealing condition are uniform,dense,with good crystallinity.Meanwhile,device performance has also been improved,efficiency up to 7.78%and has excellent environmental stability.（2）Research on preparation and performance of all-inorganic visible semitransparent solar cells based on CsPbIBr₂.Firstly,the traditional Spiro-OMe TAD hole transport layer and Au electrodes are replaced by NiO_X and ITO,respectively.The average transmittance of the former in the400-800 and 600-800 nm wavelength range is 46.9%and 73.1%,the average photoelectric conversion efficiency is 7.35%,while the latter is only 18.8%and 28.7%in the corresponding wavelength range,with an average efficiency of 6.67%.In addition,the semitranslucent device based on NiO_X and ITO shows better moisture resistance stability.These phenomena can be attributed to a higher matching degree of energy level between the inorganic hole transport layer NiO_X and perovskite,and good stability of NiO_X materials.Further,a series of Cs_1-xRb_xPb IBr₂（x=0-0.03）perovskite is prepared by doping a small amount of Rb to substitute Cs.The effects of different Rb content on perovskite film absorbance,grain size and device performance are systematically.The results show that Cs_0.98Rb_0.02Pb IBr₂-based visible semitranslucent solar cells have best performance,efficiency achieves 8.30%.（3）Research on preparation and performance of flexible perovskite solar cells based on all-inorganic CsPbIBr₂.The annealing temperature of CsPbIBr₂ perovskite film is reduced by precursor solvent engineering to realize the preparation of flexible solar cells with polyethylene naphthalate（PEN）as substrate.The effects of different acetone concentration in precursors on perovskite are compared.The best concentration is selected to fabricate visible semitranslucent flexible device with an efficiency of7.80%.Moreover,the open voltage is raised to 1.20 V which is mainly due to the increase in grain size promoted by acetone solution.