Energy Funneling from Water-Dispersed Perovskites to Chromophores

Cesium lead halide perovskite nanocrystals (PNCs) have enjoyed enormous attention in optoelectronics and photovoltaics. However, instability under polar conditions and limited energy/charge transport due to long-chain capping ligands restrict their large-scale applications. We have engineered a short-chain multidentate bolaamphiphilic ligand (NKE-3), which provides synergistic passivation of the perovskite surface by one multidentate ionic terminal and localizes water molecules by another multidentate ionic terminal, leading to a water-suspended colloidal solution of PNCs. NKE-3 allows efficient long-range dipole-based fluorescence resonance energy transfer (FRET) from perovskites to Rhodamine B isothiocyanate (RITC) in water, with FRET efficiencies ranging from 96% to 98%. We calculated the FRET rate using the acceptor’s rise-time component, as it ensures no contamination from FRET-inactive donors. Moreover, we tuned the emission maxima of PNCs through halide exchange to optimize FRET efficiency. Such energy funneling to a suitable molecular photocatalyst is imperative for PNCs’ potential applications.