Fig. 2From: Water-stable, biocompatible, and highly luminescent perovskite nanocrystals-embedded fiber-based paper for anti-counterfeiting applicationsOptical properties of the PCL-perovskite fibers. a Photograph of the fabricated PCL-perovskite fibers. b PL emission spectrum obtained for the PCL-perovskite fibers. c PL excitation spectrum obtained for the PCL-perovskite fibers. d Photograph of the PCL-perovskite fibers in water expose to normal light and UV lightBack to article page