The two-step blade-coating method exhibits several advantages such as simple operation and high reproducibility, making it a promising scalable deposition process for high-efficiency perovskite solar cells. However, a large number of defects exist at the interface, leading to nonradiative carrier recombination losses, which negatively impact device performance and stability. Introducing pyridine derivatives at the interface to passivate defects is an effective strategy. However, most pyridine-derived molecules are used in large quantities and high concentrations, which compromises process reproducibility, reduces manufacturing reliability, and increases production costs. This study demonstrates the introduction of 3,5-Difluorpyridin-2,6-Diamin (2NF-Py) molecules at the perovskite/hole transport layer interface. Through the –NH2 group and pyridine nitrogen on the 2NF-Py molecule, which interact with interfacial uncoordinated Pb2+ and free I–, defects are effectively passivated. Meanwhile, the F group on the 2NF-Py pyridine ring increases the electrostatic center shift, thereby improving its reaction activity and enhancing its defect passivation capability. As a result, an efficiency increases from 18.07 to 21.82% was achieved at a low concentration of 0.2 mg/mL, marking the highest efficiency for perovskite solar cells (PSCs) fabricated using a two-step blade-coating process without additional assistance and the device maintained 90% of its initial efficiency after being placed in air for 1536 h.
This paper proposes a polyvinyl alcohol/AlFFIVE-1-Ni (PVA/KAUST-8)-coated long-period fiber grating (LPFG) SO 2 concentration sensor to accurately monitor SO 2 concentrations online. To enhance the adhesion strength between the fiber and a SO 2 -sensitive film, the etched LPFG surface was silanized using 3-aminopropyltriethoxysilane, and then coated with a PVA/KAUST-8 SO 2 -sensitive sol using the doctor blading method. A fluorosilane hydrophobic coating was deposited on the SO 2 -sensitive membrane surface and integrated with a LPFG temperature sensor, thereby effectively eliminating measurement interference caused by ambient temperature and humidity fluctuations during SO 2 concentration detection. The morphology and composition of the SO 2 -sensitive films were characterized using optical microscopy, field-emission scanning electron microscopy, X-ray diffraction analysis, and X-ray photoelectron spectroscopy. Furthermore, the working principle of the sensors for the detection of SO 2 was established. Under optimized parameters (LPFG diameter: 60 μm; PVA doping in PVA/KAUST-8: 12 wt%; SO 2 -sensitive film: 45 μm; fluorosilane composite layers: 12) within a humidity range of 0–60 % RH and a temperature range of 25–45 °C, the sensor demonstrated a good selective SO 2 detection with 2.79 pm/ppm sensitivity, 1.07 ppm detection limit, 390 s response time, and 8.89 % maximum relative error.
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