Direct ambient synthesis of cerium-sensitized Cs₃TbCl₆ microcrystals with near-unity photoluminescence quantum yield and robust stability for white lighting

Recently, lead-free zero-dimensional Cs₃TbCl₆ (CTC) microcrystals have shown great potential for applications in light-emitting diodes. However, two major limitations of CTC are their low absorption coefficient and harsh preparation. In this study, Ce³⁺ with 4f–5d orbital coupling was used to dope CTC, enabling the excitation band to shift from UV-B to UV-A and elevating the photoluminescence quantum yield from 33.52% to 96.43%. In addition, cerium-sensitized CTC microcrystals (MCs) with different dopant ratios were obtained to study the energy transfer process from Ce³⁺ to Tb³⁺, which were prepared via a simple monosolvent ethanol-assisted recrystallization method at room temperature. Finally, we used cerium-sensitized CTC MCs with excellent stability to fabricate the white light-emitting diodes. This work not only offers a deep understanding of competitive energy transfer in zero-dimensional lanthanide-based metal halides, but also presents a direct ambient synthesis strategy of highly emissive and robustly stable phosphor for white light illumination.