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-4f energy gap with a root-mean-square error of ca. 0.03 eV (7.0 nm). By incorporating this luminescence predictor into a high-throughput screening of 223 nitride materials in the Inorganic Crystal Structure Database, we identify and experimentally validate (Sr,Ba)₃Li₄Si₂N₆:Eu(II) with NIR emissions of λ_em = 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 λ_em 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.