In the realm of renewable energy, there has been a growing focus on improving the efficiency and stability of solar cells. One of the emerging technologies that has garnered significant attention is organic solar cells based on perovskite materials. These cells offer various advantages over traditional silicon-based solar cells, including lower fabrication costs, greater flexibility, and tunability. However, despite their potential, organic solar cells have thus far fallen short in terms of power conversion efficiency (PCE) when compared to silicon solar cells.
One of the proposed strategies to enhance the efficiency and stability of organic solar cells involves combining them with cells based on mixed halide wide-bandgap perovskites. This approach aims to create perovskite/organic tandem solar cells that could potentially achieve high PCEs and stabilities. However, the performance of these tandem cells is currently hindered by a phenomenon known as phase segregation. This process negatively impacts the efficiency of wide-bandgap perovskite cells and subsequently affects recombination processes at the interconnecting layer of the tandem solar cells.
Researchers at Soochow University’s Suzhou Key Laboratory of Novel Semiconductor-optoelectronic materials and devices have recently made significant strides in addressing the issue of phase segregation in wide-bandgap perovskites. Their innovative strategy, detailed in a publication in Nature Energy, involves the incorporation of a pseudo-triple-halide alloy in mixed halide perovskites based on iodine and bromine. By introducing pseudo-halogen thiocyanate ions into the perovskite lattice, the researchers were able to prevent halide elements from segregating within the solar cells, thus improving crystallization and reducing grain boundaries.
The introduction of pseudo-halogen thiocyanate ions into iodine/bromide mixed halide perovskites proved to be effective in suppressing phase segregation and enhancing the performance of wide-bandgap perovskites. By slowing down crystallization, the thiocyanate ions prevented ion migration, facilitating the movement of electric charge in the solar cell. Moreover, the SCN ions occupied iodine vacancies, thereby blocking halide ion migration through steric hindrance. These effects collectively contributed to reducing energy loss in the wide-bandgap perovskite cells.
Through their innovative approach, the researchers were able to develop perovskite/organic tandem solar cells that demonstrated promising results. The tandem cells achieved a PCE of 25.82%, a certified PCE of 25.06%, and an operational stability of 1,000 hours in initial tests. This breakthrough opens up possibilities for the adaptation and application of the methodology to a wider range of wide-bandgap perovskites with different compositions. As a result, the development of stable and efficient perovskite/organic photovoltaics that can operate effectively under varying light intensities for extended periods may become a reality in the near future.
The advancement of perovskite/organic tandem solar cells represents a significant step forward in the quest for efficient and stable renewable energy solutions. By addressing the challenges of phase segregation in wide-bandgap perovskites, researchers have paved the way for the development of high-performance solar cells that hold great promise for the future of photovoltaics. Continued research and innovation in this field will be crucial in further enhancing the efficiency, stability, and longevity of solar energy technologies.
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