Nature of Self-Trapped Exciton Emission in Zero-Dimensional Cs2ZrCl6 Perovskite Nanocrystals

Low dimensional perovskite-inspiredmaterials with self-tappedexciton (STE) emission have stimulated a surge of cutting-edge researchin optoelectronics. Despite numerous efforts on developing versatilelow-dimensional perovskite-inspired materials with efficient STE emissions,there is little emphasis on the intrinsic dynamics of STE-based broademission in these materials. Here, we investigated the excited statedynamics in zero-dimensional (0D) Cs2ZrCl6 nanocrystals(NCs) with efficient blue STE emission. By using femtosecond transientabsorption (fs-TA) spectroscopy, the ultrafast STE formation processwithin 400 fs is directly observed. Then, the formed STEs relax toan intermediate STE state with a lifetime of & SIM;180 ps beforereaching the emissive STE state with a lifetime of & SIM;15 & mu;s.Our work offers a comprehensive and precise dynamic picture of STEemission in low-dimensional metal halides and sheds light on extendingtheir potential applications.