Harnessing Dual Violet Emission in Cerium-Based Perovskite Derivatives for Solution-Processed Next-Generation Lighting

Violet emission is a compelling area in display technology, with wide-bandgap materials featuring high exciton binding energies being preferred. However, the limited violet emission efficiency of lead halide perovskites constrains their application in violet lighting. Here, we present a wide-bandgap cerium (Ce)-based perovskite derivative, Cs₃CeBr₆, as a promising alternative. To overcome the challenges of synthesis complexity, we develop a simple, water-based synthesis method for Cs₃CeBr₆ powders. These materials exhibit dual violet emission peaks at 392 and 421 nm, corresponding to parity-allowed high-energy transitions in Ce³⁺, with a short excited-state lifetime of ∼29 ns. Owing to the high exciton binding energy of ∼180 meV, Cs₃CeBr₆ is implemented as the active layer in fully solution-processed violet LEDs, achieving pure violet luminance and an external quantum efficiency (EQE) of 0.44%. These results highlight the potential of solution-synthesized Cs₃CeBr₆ as an efficient material for violet lighting applications.