Environmentally-Friendly\nEuropium-Based Yellow Perovskite\nNanocrystals with Near-Unit Efficiency for White LED

Recently,\nMn<sup>2+</sup>-doped metal halide perovskites (MHPs)\nhave been extensively studied as they can improve the photoluminescence\nquantum yield (PLQY) with minimal self-absorption. However, almost\nall of them with high efficiency are Pb/Cd-based toxic heavy metal\nperovskites, which seriously limits their commercial applications.\nTo address the dual needs of high efficiency and environmental protection,\nthis study proposes to incorporate Mn<sup>2+</sup> into the environmentally\nfriendly perovskite CsEuX<sub>3</sub> (X = Cl/Br), and further increases\nPLQY to 96.9% through the codoping of Tb<sup>3+</sup>, which, to the\nbest of our knowledge, is the highest reported value of all inorganic\nenvironmentally friendly perovskites in the visible light region.\nIt is found that the codoping of Tb<sup>3+</sup> can reduce the host\ndefect density and enhance the crystal field strength around Mn<sup>2+</sup>, acting as an energy transfer bridge. Additionally, Mn<sup>2+</sup>/Tb<sup>3+</sup>-codoped CsEuX<sub>3</sub>-based white light-emitting\ndiodes (WLEDs) with a high color rendering index (Ra = 91.2) demonstrate\npotential for lighting applications.