Ultrahigh stable lead halide perovskite nanocrystals as bright fluorescent label for the visualization of latent fingerprints.

Fingerprints formed by the raised papillary ridges are one of the most important markers for individual identification. However, the current visualization methods for latent fingerprints (LFPs) suffer from poor resolution, low contrast, and high toxicity. In this work, the CsPbBr/CsPbBrnanostructured composite crystal (CsPbBr/CsPbBrNCC) were synthesized via a simple chemical solvent-assisted method. Compared with conventional perovskites, the as-prepared CsPbBr/CsPbBrNCC present an outstanding long-term environmental and water stability with 42% and 80% photoluminescence intensity remaining after 28 d under water and air conditions, respectively. Moreover, a special response to biomolecules from fingerprints was observed due to the hydrophobic interactions between the CsPbBr/CsPbBrNCC surface hydrophobic ligands (oleyl amine and oleic acid) and the hydrophobic groups in the biomolecules from the human fingers. Clear LFPs images were visualized in a bright environment illuminating the prepared CsPbBr/CsPbBrNCC powder under UV light of wavelength 365 nm. The images were also obtained on porous and non-porous surfaces such as metal, plastic, wood, glass, and paper products. These perovskite nanocrystals are expected a stable and bright luminescent labeling agent for LFPs visualization and have potential application in crime scene and personal identifications.