Efficiency breaks through 25%! Wide bandgap perovskite solar cells, innovative strategies to suppress phase separation!

• This study successfully suppressed the halide phase separation problem in wide-bandgap perovskites by introducing pseudohalogen thiocyanate ions (SCN) into iodine/bromine mixed halide perovskites.

  
  

  Experimental results show that this improved perovskite/organic tandem solar cell achieves a photoelectric conversion efficiency of 25.82% (certified efficiency is 25.06%) and maintains stability after 1,000 hours of continuous operation.

  
  

  Graphical guide

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• Figure 1: Shows the scanning electron microscope images, in-situ absorption spectra, absorption intensity changes of Cs0.2I1.6 and Cs0.2I1.6 + Pb(SCN)2 perovskite films by adjusting the perovskite crystallization process. Space charge limited current measurements.
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• Figure 2: Describes the characteristics of pseudo-trihalide alloy perovskite, including color reaction with FeCl3, absorption spectrum, band structure changes, tDOS spectrum, and the effect of Pb(SCN)2 doping on halogen vacancies and occupied VI .
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• Figure 3: Analysis of ion migration behavior and halide phase separation, including DFT calculated I-migration paths, Arrhenius plots of ion migration activation energies, GIWAXS measurements, photoluminescence (PL) evolution, and changes in absorption spectra.
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• Figure 4: Demonstrating the performance of single-junction cells and tandem solar cells, including JV curves, maximum power point (MPP) operating stability, device structure and cross-sectional scanning electron microscope images of tandem solar cells, EL spectra, and open circuit voltage (Voc) Estimate of contribution.

  
  

  Highlights

  
  

  1. By introducing SCN ions, the photoelectric conversion efficiency of perovskite/organic tandem solar cells was successfully increased to 25.82%, with a certified efficiency of 25.06%.

  
  

  2. Experimental results show that the improved perovskite solar cell still exhibits good stability after 1,000 hours of continuous operation.

  
  

  3. This research provides an effective strategy to solve the halide phase separation problem in wide-bandgap perovskite, and helps to improve the performance and stability of perovskite solar cells.

  
  

  high-end representation

  
  

  This paper uses a variety of high-end characterization techniques to deeply analyze the structure and properties of perovskite materials.

  
  

  In-situ testing: In-situ absorption spectroscopy technology was used in the study to monitor the spectral changes of the perovskite film during the initial annealing process. Through this technique, the authors were able to observe the crystallization behavior of the perovskite film in real time and found that the Pb(SCN)2-doped perovskite film exhibited stronger absorption intensity during the growth stage, indicating its enhanced crystallinity. .

  
  

  In addition, in-situ photoluminescence (PL) spectroscopy was also used to analyze the defect density and carrier lifetime of the film. The results showed that the perovskite film doped with SCN ions has a lower defect density and stronger PL intensity.

  
  

  Synchrotron radiation: GIWAXS (Grazing Incidence Wide-Angle X-ray Scattering) measurement using synchrotron radiation light source in the article. This technique can provide information on the crystal structure and phase distribution of perovskite films.

  
  

  Through GIWAXS measurements, the authors studied the phase separation of perovskite films after light aging and found that perovskite films doped with SCN ions showed better structural stability under light exposure.

  
  

  computational simulation

  
  

  In this paper, the authors used computational simulation methods to gain a deeper understanding of the physical properties and ion migration behavior of perovskite materials.

  
  

  DFT calculation: The article uses Density Functional Theory (DFT) calculation to analyze the defect formation energy and ion migration path in perovskite.

  
  

  Through DFT calculations, the researchers were able to predict the stability and distribution of SCN− ions in the perovskite lattice, as well as their impact on the perovskite structure.

  
  

  Calculation results show that the doping of SCN− ions can increase the formation energy of halogen vacancies in perovskite, thereby inhibiting the migration of halogen ions. In addition, DFT calculations also revealed the occupancy preference of SCN− ions in the perovskite lattice and how they hinder the migration of I− ions through steric hindrance effects.