Environmentally-Friendly Europium-Based Yellow Perovskite Nanocrystals with Near-Unit Efficiency for White LED

Recently, Mn²⁺-doped metal halide perovskites (MHPs) have been extensively studied as they can improve the photoluminescence quantum yield (PLQY) with minimal self-absorption. However, almost all of them with high efficiency are Pb/Cd-based toxic heavy metal perovskites, which seriously limits their commercial applications. To address the dual needs of high efficiency and environmental protection, this study proposes to incorporate Mn²⁺ into the environmentally friendly perovskite CsEuX₃ (X = Cl/Br), and further increases PLQY to 96.9% through the codoping of Tb³⁺, which, to the best of our knowledge, is the highest reported value of all inorganic environmentally friendly perovskites in the visible light region. It is found that the codoping of Tb³⁺ can reduce the host defect density and enhance the crystal field strength around Mn²⁺, acting as an energy transfer bridge. Additionally, Mn²⁺/Tb³⁺-codoped CsEuX₃-based white light-emitting diodes (WLEDs) with a high color rendering index (Ra = 91.2) demonstrate potential for lighting applications.