All‐In‐One Double Perovskite Flexible Film with Highly Efficient Warm‐White Emission, Near‐Infrared Emission, and X‐Ray Radioluminescence

Abstract Recently, lead‐free double perovskites have gained much attention for their superior optoelectronic properties. However, realizing efficient white light and near‐infrared (NIR) emission, as well as bright radioluminescence (RL) in a single compound has not yet been reported. Herein, Bi³⁺/Mo⁴⁺‐codoped Cs₂Ag_0.6Na_0.4InCl₆ double perovskite is synthesized by a hydrothermal reaction. Under photoexcitation, the codoped compound exhibits highly efficient broadband warm‐white emission (610 nm) and NIR emission (930 nm), which can be attributed to self‐trapped exciton emission of Bi³⁺ and d–d transition of Mo⁴⁺, respectively. Interestingly, Bi³⁺/Mo⁴⁺‐codoped Cs₂Ag_0.6Na_0.4InCl₆ also emits strong radioluminescence with a light yield of 25100 photons per MeV under X‐ray irradiation. Based on Bi³⁺/Mo⁴⁺‐codoped Cs₂Ag_0.6Na_0.4InCl₆/PDMS flexible film, its applications in white light emitting diodes (WLED), NIR light source, and X‐ray scintillator are demonstrated, respectively, all of which exhibit remarkable optoelectronic properties. Finally, the as‐fabricated devices in white light, NIR, and X‐ray imaging are further demonstrated respectively, and the pixel‐level white light, NIR, and X‐ray image fusion is realized without pixel mismatch and complex imaging processing. Therefore, the internal information of the capsule wrapped with centrifuge tube and iron wire is successfully demonstrated through X‐ray to NIR image fusion.