A research team led by South Korea's Gwangju Institute of Science and Technology (GIST) has fabricated a mini perovksite module with an active area of 24.8 cm2 and a power conversion efficiency of 22.56%.
The researchers explained that as the area of a solar cell or mini-module increases, forming a uniform perovskite layer becomes more challenging. This non-uniformity increases electron losses during charge transport, resulting in reduced efficiency and stability.
To address this issue, the team focused on engineering the interface of the electron transport layer (ETL). They selected tin oxide (SnO₂), the most commonly used ETL material in perovskite solar cells. However, SnO₂ typically exhibits poor surface wettability, which can lead to uneven perovskite films and microscopic defects that act as electron loss pathways.
To overcome this limitation, the scientists adopted what they described as a “simple” approach, incorporating the polymer polyethyleneimine (PEI) into the SnO₂ layer during the initial ETL formation process.
“PEI fills microscopic defects on the SnO₂ surface, reducing electron loss and improving the electrical environment at the interface, thereby facilitating smooth electron transport,” the researchers said. “This lowers the electron transport barrier within the solar cell, simultaneously improving efficiency and stability.”
They added that by precisely controlling the ETL interface, high-quality perovskite films could be produced with minimal performance variation, even over large areas and without additional processing steps. “This approach is particularly advantageous for manufacturing methods suitable for mass production, such as printing-based thin-film processes,” the team noted.
Using this device architecture, the researchers achieved a power conversion efficiency of 24.49% in a small-area cell and 22.56% in the mini-module. The mini-module was also found to retain 94% of its initial performance after 500 hours of operation.
“High efficiency and stability were consistently maintained not only in small-area cells but also in large-area solar cell modules, significantly enhancing the prospects for mass production and commercialization,” the researchers said.
The new cell design was presented in “Dual-Function Interface Engineering of SnO2 Electron Transport Layers: Wettability Enhancement and Work Function Tuning for Efficient and Stable Perovskite Solar Cells and Minimodules,” which was recently publish in nano micro small.
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