This may be that when the metal ions reach a certain amount, the coordination effect with the guest molecules reaches the maximum, so the effect on the doped materials will tend to be stable. Furthermore, the low solubility of metal salts in the host also limits the maximum metal ion content that the doped system can contain. Therefore, other three-component doped materials with a guest-host-metal salt molar ratio of 1:1000:5 were prepared.