Strategies for stabilizing 3D/2D perovskite heterostructures for solar cells
Hybrid perovskite solar cells (PSCs) made of organic and inorganic materials are very promising energy solutions that could help reduce carbon emissions worldwide. In recent years, the energy conversion efficiency (PCE) of these cells has improved significantly, eventually exceeding 25%.
A major milestone in the fabrication of efficient PSCs is the use of 2D and quasi 2D modified 3D. perovskite heterostructures (that is, structures composed of 3D and 2D perovskite materials). These structures have a number of favorable qualities, such as that they allow passivation of defects and favorable band alignment, thereby improving the open-shift voltage and cell fill factor.
3D/2D heterostructures are typically produced by spin coating an organic cationic salt solution on top of a 3D perovskite material and forming a thin 2D perovskite layer on its surface. However, this process can facilitate further degradation of heterostructures under some conditions, due to the diffusion of ions between the 2D perovskite surface and the underlying bulk 3D perovskite.
Researchers at Huazhong University of Science and Technology, Wuhan University of Technology, and the University of Toronto recently introduced a new method to fabricate more stable 3D/2D heterostructures that prevent their degradation. Their approach, introduced in a paper published in natural energy, which requires the introduction of an additional layer between the structs; 3D and 2D perovskite layers.
“Ion diffusion between the 2D surface and the bulk 3D perovskite leads to the degradation of the 3D/2D perovskite heterostructure and limits the long-term stability of PSCs,” said Long Luo, Haipeng Zeng and colleagues. their wrote in their paper. “We incorporated a cross-linked polymer (CLP) on top of the 3D perovskite layer and then placed the 2D perovskite layer through a steam-assisted two-step process to form the 3D/CLP/2D perovskite. heterostructure.”
Essentially, Luo, Zeng and their colleagues proposed to introduce an interlayer between 3D bulk perovskite and 2D surface perovskite in a 3D/2D heterostructure. This interlayer is made of a cross-linked polymer (CLP) that can inhibit ion diffusion without affecting the charge transport between the 3D and 2D perovskite layers.
“Luminescence spectroscopy and thickness profile elemental analysis indicate that CLP stabilizes the heterostructure by inhibiting the diffusion of cations (formamidinium, FA+ and 4-fluorophenylethylene, 4F-PEA+) between 2D and 3D perovskites,” Luo and colleagues explain in their paper.
To test the effectiveness of their updated 3D/2D heterostructure design, the researchers used it to create a series of small-area solar cells, as well as mini-solar cells. solar module. These cells and modules have achieved remarkable results, as they appear to be significantly more stable than perovskite-based cells and modules of conventional 3D/2D heterostructure design.
“For the carbon electrode-based devices, we report small-area devices with 21.2% efficiency and small modules with 19.6% efficiency,” said Luo and colleagues. written in their paper. “Instruments retain 90% of their original efficiency after 4,390 hours of operation under maximum power point tracking conditions and lighting a high-temperature sun.”
In the future, the new design introduced by Luo and colleagues could help with stability solar battery based on 3D/2D perovskite heterostructures without affecting their efficiency. Alternatively, their study may inspire other groups to devise similar methods that introduce an interlayer between the 3D and 2D perovskite layers to prevent ion diffusion-induced degradation.
Long Luo et al., Stabilization of 3D/2D perovskite heterostructure through ion diffusion inhibition by cross-linked polymers for solar cells with improved efficiency, natural energy (2023). DOI: 10.1038/s41560-023-01205-y
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