Exploration of Nontoxic Cs3CeBr6 for Violet Light-Emitting Diodes

Violet light-emitting diodes (LEDs) are widely utilized for solid-state lighting, bacteria sterilization, and so on. Herein, the nontoxic and earth-abundant Ce3+ ion with intrinsic strong violet emission is introduced to substitute Pb2+ in CsPbBr3 perovskite for electrically driven PeLEDs. Cs3CeBr6 possesses a zero-dimensional photoactive site with a high photoluminescence quantum yield of ≈90% for both crystals and films. The excited-state lifetime of ≈28 ns enabled by the spin- and parity-allowed Ce-5d → Ce-4f transition is considerably faster than other lanthanide-based luminescent centers. The violet LEDs based on thermally evaporated Cs3CeBr6 films display color-stable spectra with a maximum EQE of 0.46%, representing the first Cs3CeBr6 LED and one of the most efficient violet PeLEDs. Moreover, a white LED with standard color coordinates of (0.339, 0.343) is constructed by combining Cs3CeBr6-based violet PeLEDs with yellow phosphor downconverters. Our work will motivate further exploration of diverse lanthanide-based perovskites for LEDs and other optoelectronics.