Efficient blue-light-excitable broadband NIR emission in Mo4+-doped double perovskite with robust thermal stability and efficient X-ray scintillation for pixel-level X-ray to NIR image fusion
Lead-free double perovskites are promising for optoelectronic applications due to their tunable optical properties, stability, and non-toxicity. However, achieving efficient ultrabroadband near-infrared (NIR) emission and X-ray radioluminescence (RL) simultaneously remains challenging. Here, we report a Mo4+-doped Cs2(Na0.4Ag0.6)InCl6 double perovskite that exhibits efficient blue-light-excitable NIR emission with a near-unity photoluminescence quantum yield. The emitter demonstrates robust thermal stability, retaining 84% of its initial emission intensity at 420 K relative to 300 K. Under X-ray irradiation, the material shows bright NIR RL with a high light yield of 39,400 ± 1100 photons/MeV. A flexible film of Mo4+-doped Cs2(Na0.4Ag0.6)InCl6/polydimethylsiloxane (PDMS) was fabricated and applied as an NIR light source and X-ray scintillator. A dual-functional platform for cooperative NIR and X-ray imaging was established using a bullfrog palm as the target, achieving pixel-level fusion of NIR and X-ray images without spatial mismatch or complex image processing. The fused image simultaneously visualizes blood vessels and skeleton textures under the skin tissue. This work provides a viable strategy for lead-free double perovskites in advanced optoelectronic devices, particularly for multispectral imaging.