Comparison of X-ray Luminescence of CdSe _0.02 S _0.98 , LaF ₃ :Ce ³⁺ /CdSe _0.02 S _0.98 , and CsPbI ₃

CdSe _0.02 S ^0.98 quantum dots (QDs), LaF ₃ :Ce ³⁺ /CdSe _0.02 S ^0.98 nanocomposites (NCs), and CsPbI ₃ QDs were prepared to compare the properties of photoluminescence (PL) and X-ray excited luminescence (XEL) in these materials. CdSe _0.02 S _0.98 QDs have an intense PL peak but negligible XEL. The LaF ₃ :Ce ³⁺ /CdSe _0.02 S _0.98 NCs have a single XEL peak and a corresponding PL peak. The XEL peak in LaF ₃ :Ce ³⁺ /CdSe _0.02 S _0.98 NCs originates from a resonance energy transition from LaF ₃ :Ce ³⁺ nanocrystals to CdSe _0.02 S _0.98 QDs. The CsPbI ₃ QDs, which contain the heavy element Pb (atomic number Z = 82), exhibited a higher XEL than the CdSe _0.02 S _0.98 QDs and the LaF ₃ :Ce ³⁺ /CdSe _0.02 S _0.98 NCs.