In the quest for alternative energy sources, solar cells play a crucial role. However, researchers constantly face the challenge of increasing conversion efficiency and maintaining long-term stability. In a groundbreaking study published in Nature, scientists from the Hefei Institutes of Physical Science (HFIPS) have proposed a new method to fabricate homogenized perovskite films for solar cells, with promising results.
Lead-halide perovskite solar cells (PSCs) have been extensively studied for their high efficiency. However, there has been a noticeable slowdown in the growth rate of conversion efficiency. Previous studies focused primarily on the surface, dopant, and component levels. Recognizing the limitations of these approaches, Pan Xu and his team decided to investigate the phase level, where they discovered an important factor impacting both efficiency and stability.
Throughout the years of research in the field, the scientists at HFIPS observed that phase segregation occurs within perovskite films, causing detrimental effects. In an effort to understand this phenomenon further, experimental approaches were employed to quantify the distribution of cations FA+ and Cs+ vertically. Their findings showed that Cs+ tends to aggregate at the bottom of the film, while FA+ accumulates at the upper interface. These observations were further supported by studies on the distribution in the crystalline phase.
With a clearer understanding of the inhomogeneous distribution, the researchers focused on determining the underlying reasons. Through in-situ tests, they discovered that the crystallization and phase transition rates of cations in different groups were significantly different. This discrepancy in rates was identified as the primary cause of the observed inhomogeneity.
Armed with this knowledge, the team proposed a strategy to address the challenge. They introduced 1-(Phenylsulfonyl)pyrrole (PSP) as an additive to compensate for the differences in crystallization and phase transition rates. The implementation of this strategy yielded remarkable results, with conversion efficiency increasing to 25.8% under third-party certification.
In addition to improved efficiency, the perovskite films demonstrated excellent long-term stability. Even after 2,500 hours of maximum power point tracking, the conversion efficiency remained as high as 92% of the original value. This achievement is a significant milestone in the field, tying the existing record in conversion efficiency.
Pan Xu and his team at HFIPS have paved the way for advancements in solar cell technology by focusing on phase optimization. Their findings on the impact of phase segregation and the introduction of an additive to produce homogenized films offer promising solutions for increasing conversion efficiency and stability. As the global pursuit of alternative energy sources continues, this research provides valuable insights and paves the way for further innovation in the field of solar cells.