Unlocking Enhanced Light Harvesting in Perovskites: A Light‐Mediated Ligand Management Approach

Abstract Interfaces between nanocrystals and their stabilizing ligands in light‐harvesting devices are crucial for mediating energy transfer, essential for efficient solar energy conversion. In metal halide perovskites, a promising material for these devices, Förster resonance energy transfer (FRET) within perovskite/acceptor‐molecule complexes offers a pathway for optimized energy transfer. However, traditional methods for optimizing FRET in perovskite‐chromophore hybrids are based on static modifications. This study presents an innovative approach for light‐driven dynamic control of FRET, achieving an ≈14% enhancement in efficiency between CsPbBr₃ nanocrystals (CPB NCs) and rhodamine B isothiocyanate (RITC) dye. UV light is utilized to reversibly regulate NC‐ligand binding and thus control the coupling between CPB NCs and RITC at their interface. This approach critically relies on strong NC–ligand interactions, such as the Pb─S bond between CPB NCs and RITC. Light exposure weakens the binding of surface ligands, allowing RITC, with its strong bond, to attach more effectively and promote enhanced energy transfer. This light‐activated control is absent with Rhodamine B (RhB) lacking ─NCS group, a strong binding motif. The findings reveal the importance of NC–ligand interactions in dynamically manipulating FRET with light. This pioneering method for nanoscale FRET control paves the way for more efficient light‐harvesting devices.