Commercial laser treatment to boost perovskite solar cell performance


A European research team has sought the improve performance and efficiency of a perovskite solar cell by passivating surface defects in the perovskite film via commercial laser treatment.

“Our work is a proof of concept, and we are consistently working on advanced results,” corresponding co-author Monika Rai, told pv magazine, noting that the proposed approach is solvent-free and industrially scalable.

They used an industrial nanosecond pulsed ultraviolet (UV) laser at two different energy intensities of 160 nJ and 650 nJ, respectively.

They then utilize scanning electron microscopy (SEM) and X-ray diffraction (XRD) measurements to evaluate the effect of the laser pulse on the morphology of the film and found that both intensities result in a uniform grain size distribution and clear grain boundaries, although the higher intensity also showed some degraded perovskite grains.

By contrast, the laser pulse with the lower intensity did not damage the perovskite surface or affected any bulk properties of the perovskite thin film. “There is no observable difference in the binding energy or broadening of the spectra at the low laser energy, which suggests a negligible change in the chemical properties at the perovskite surface,” the researchers said. “At high laser energy, the overall absorption decreases due to obvious destruction in the film, as supported by XRD and SEM measurements.”

The team applied the treatment to a solar cell based on triple-cation cesium methylammonium formamidinium (CsMAFA) and found its efficiency grew from 18.0% to 19.3%, with the stability performance being also improved. “At optimized energy, the laser-polished devices show improved open-circuit voltage (VoC) and fill factor, owing to reduced interface recombination losses, unlocking the potential of high Voc from the perovskites of similar bandgaps,” they said, adding that the cell achieved a remarkable Voc of 1.21 V.

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The cell was able to retain around 90% of its initial efficiency for 1,000 h compared to 75% for a reference device to which the laser treatment was not applied.

“This technique may be particularly suitable for roll-to-roll (R2R) production lines,” co-author Micahel Saliba told pv magazine.

Details on the approach, the laser power fine-tuning, and the measurement methods are documented in “Light Makes Right: Laser Polishing for Surface Modification of Perovskite Solar Cells,” published in ACS Energy Letters. The research group includes scientists from the University of Stuttgart and the Brandenburg University of Technology Cottbus–Senftenberg in Germany, the University of Luxembourg, and the University of Valencia in Spain.



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