[Matter] Efficient Near-infrared Phosphors Discovered by Parametrizing the Eu(II) 5d-to-4f Energy Gap
Summary: Inorganic materials with rare-earth activators (e.g., Ce, Eu) exhibit broad 5d-to-4f emission spectra characterized by a strong host material dependency. Despite extensive research, the development of an efficient and near-infrared (NIR) 5d-to-4f emission remains elusive. Herein, we introduce key descriptors of the Eu(II)-host interactions and predict the in-crystal 5d-to-4f3Li4Si2N6:Eu(II) with NIR emissions of λem = 800 ∼ 830 nm and high quantum efficiencies (QEs) of 30% ∼ 40%, leading to an NIR light power ∼3× superior to prevailing NIR emitters. The ultralong λem and high QE stem from a coordinated energy transfer and an optimized electronic delocalization around Eu(II). This work provides a cost-efficient computational approach for discovering phosphors with desired emissions.