During implementation, the color shifting layer 280 may be made of an organic photochromic material containing spirooxazine and also may be made of an organic photochromic material containing spiropyran. The above two organic photochromic materials are common materials in the related art and can be obtained through purchase. Since the organic photochromic material is selected to prepare the color shifting layer 280, the damping periods of the photochromic reaction and its reverse reaction of the color shifting layer 280 can be reduced to be more than ten micro seconds and less than twenty micro seconds, such that the color shifting layer 280 can be quickly switched between the excited state and the unexcited state after the ultraviolet light is received or the ultraviolet light disappears. Therefore, a quick unlocking can also be achieved in sunlight, and an unlocking speed is increased. According to related experiments, when the color shifting layer 280 of this embodiment is used, it is ensured that the time of the color shifting layer being switched between the excited state and the unexcited state ranges from 0.5 to 1 second.

In this embodiment, the color shifting layer 280 may be arranged to the substrate 233 by means of vacuum evaporation. The vacuum evaporation is a processing method, in which a certain heating and evaporation method is used to evaporate and vaporize a coating material (i.e. the organic photochromic material) under a vacuum condition, and then particles fly to a surface of the substrate and cohere into a film. The evaporation is a vapor deposition technology which is used early and widely, and has advantages of the simple forming method of the film, the high purity and compactness of the film, and the unique structure and performance of the film, etc.