On November 19, 2024, Shen Chen from our group published a paper as the first author in ACS Photonics titled "Revealing Different Types of Grain Boundaries in Perovskite Films by Intensity-dependent Fluorescence Lifetime Imaging Microscopy."

  Grain boundaries in polycrystalline perovskite films play a crucial role in the transport and recombination of photogenerated carriers, thereby significantly influencing the efficiency and stability of perovskite solar cells. Although grain boundary engineering has been widely explored to optimize the performance of perovskite solar cells, the specific mechanisms by which grain boundaries affect carrier dynamics remain unclear and are a topic of considerable debate.

  In this study, we employed high-resolution, intensity-dependent fluorescence lifetime imaging microscopy (FLIM) to systematically investigate the behavior of different types of grain boundaries in hybrid perovskite films under varying illumination conditions. Our analysis revealed three distinct categories of grain boundaries：Type I grain boundaries, which are invisible under low excitation intensity and have minimal impact on carrier transport;Type W grain boundaries, which exhibit a "W-shaped" lifetime distribution under high illumination intensity, indicating significant carrier scattering at the grain boundary;Type V grain boundaries, which show a "V-shaped" lifetime distribution, suggesting their unique role in regulating carrier dynamics.

  These findings provide key insights into how different types of grain boundaries govern photocarrier behavior and establish a new framework for understanding the diverse effects of grain boundaries on the optoelectronic properties of perovskite films. Our results highlight the importance of targeted grain boundary engineering strategies, offering valuable guidance for the design and optimization of next-generation perovskite-based photonic and optoelectronic devices.