Ultrafast exciton-phonon coupling and energy transfer dynamics in quasi-2D layered Ruddlesden-Popper perovskites

Understanding the performance of perovskite solar cells is critical for advancing sustainable energy solutions. Hot-drop casted quasi-2D Ruddlesden-Popper perovskites (RPPs) exhibit remarkable efficiency and stability, making them promising for commercial applications. However, the ultrafast energy transfer and exciton-phonon interactions in these materials remain unclear. Here, we show that using advanced techniques like two-dimensional electronic spectroscopy (2DES) and transient grating (TG), we can unravel energy dynamics in hot-drop casted RPP films. Our study reveals rapid energy transfer between perovskite layers occurring within 100–220 femtoseconds and highlights how exciton-phonon coupling drives structural changes in the material. Coherent vibrational signals identify key lattice and organic cation modes, providing insights into their role in energy dissipation. These findings deepen our understanding of how 2D perovskites work and pave the way for improving the efficiency and stability of next-generation optoelectronic devices. Perovskite-based solar cells provide exceptional efficiency, but optimizing their performance requires precise control over material preparation methods. In this study, the authors use a hot-drop casting technique to fabricate 2D layered Ruddlesden-Popper perovskites and investigate exciton energy funneling dynamics through two-dimensional electronic and transient-grating spectroscopy.