High photoluminescence quantum yield near-infrared emission from a lead-free ytterbium-doped double perovskite

Yb 3+ ions substitute into Cs 2 AgBiBr 6 , specifically into the AgBr 6 5− and/or BiBr 6 3− octahedra, leading to a lead-free halide perovskite that converts UV and blue photons to near infrared photons with record 82.5% photoluminescence quantum yield.