HKUST scientists discover key microstructural factors to improve perovskite solar cells

Scientists from the School of Engineering at the Hong Kong University of Science and Technology (HKUST) have recently made a significant discovery in the field of perovskite solar cells. The research team, led by Prof. ZHOU Yuanyuan, identified the presence of concavities on the surfaces of crystal grains in perovskite thin films. These microstructural irregularities significantly affect the properties and reliability of solar cells, making them a key factor in their efficiency.

Perovskite solar cells, known for their outstanding power conversion efficiency (PCE), are already recognized as a potential replacement for traditional silicon solar cells. They offer several advantages, including lower production costs, sustainable manufacturing, and high adaptability in terms of transparency and color. Despite these advantages, the long-term stability of perovskite cells under various conditions remains a challenge for commercialization.

To address this issue, the HKUST research team focused on the microstructural aspects of the material. They found that concavities on the surfaces of crystal grains disrupt the structural continuity at the interface of perovskite films, limiting the efficiency and stability of the cells. By using the surfactant molecule potassium tridecafluorohexane-1-sulfonate, the team was able to eliminate these concavities, resulting in significant improvements in the performance of perovskite solar cells.

New method to improve efficiency
Through the application of the surfactant, the research team manipulated the evolution of stress and ion diffusion during the formation of perovskite films. This enabled improved energy retention efficiency during standardized thermal cycling, damp heat, and maximum power point tracking tests.

Prof. Zhou emphasized the importance of understanding the microstructure of perovskite materials to achieve maximum solar cell efficiency. "The structure and geometry of individual crystal grains are the source of performance for perovskite semiconductors and solar cells. By discovering the concavities on the grain surface, understanding their effects, and using chemical engineering to adjust their geometry, we are pioneering a new way of making perovskite solar cells with maximum efficiency and stability," said Prof. Zhou.

In addition to the discovery of concavities, the team used atomic force microscopy to closely examine the structural properties of perovskite films. Concavities are typically hidden microstructural factors that are often overlooked but have a significant impact on the performance of solar cells.

Zhang Yalan, a doctoral student in Prof. Zhou's research group, highlighted the importance of microstructure for perovskite solar cells and other optoelectronic devices. "Under Prof. Zhou's guidance, we have developed various new characterization methods and approaches to gather data to better understand the microstructure of perovskites," said Zhang.

Furthermore, the research team plans to continue developing and applying their findings to enhance the commercial viability of perovskite solar cells. The introduction of new techniques and improvements in the manufacturing process could lead to significant progress in this field, enabling wider use of perovskite cells across different industries.

Perovskite solar cells represent an extraordinary technology that could revolutionize the way we produce and use solar energy. With continuous research and improvements, the potential for this technology is immense, providing a more sustainable and efficient energy source for the future.

Source: Hong Kong University of Science and Technology