Effects of Metallic Ions on Photoluminescence Properties of CdSe/PAMAM Nanocomposites and their Application in Fingerprint Detection
Uniform and well-dispersed photoluminescent semiconductor CdSe(Cadmium selenium) QDs(Quantum dots) were in-situ prepared stabilized by G4.0-NH2 PAMAM dendrimers in water and effects of metallic ions such as Zn2+, Cd2+, Cu2+, Ag+, Pb2+, K+, Na+ on the photoluminescence(PL) properties of CdSe QDs were studied using spectrophotometric titration. The results show that Zn2+ and Cd2+ ions enhance the PL intensity of CdSe QDs, Cu2+, Ag+ and Pb2+ ions quench the PL intensity, while K+ and Na+ ions have no obvious effects. Those are attributed to the surface modification of CdSe QDs. Excess Cd2+ ions can reduce the non-combination centers, increase the passivation of PAMAM on the surface of CdSe QDs, and form a Schottky-like barrier which enhanced the PL efficiency. Excess Zn2+ ions can also increase the PL intensity of CdSe QDs in the same way as Cd2+ ions because of the much similar lattice parameters of CdSe and ZnSe. However, a CuSe, Ag2Se or PbSe shell on CdSe QDs emerges due to the substitution of Cd2+ ions, which leads to the decrease of band-edge emmiting of CdSe QDs. And the quenching effect of Ag+ is stonger than Cu2+ and Pb2+ because of the lower solubility of Ag2Se formed on the surface of CdSe QDs. Oil latent fingerprints deposited on tinfoil surface treated with CdSe/dendrimer NCs(Nanocomposites)、Cd2+-CdSe/ PAMAM NCs and Zn2+-CdSe /PAMAM NCs emitted bright yellow photoluminescence under ultraviolet excitation of 365nm from an UV LED in the dark., among, fingerprint treated with Cd2+-CdSe/dendrimer NCs and Zn2+-CdSe /PAMAM NCs was detected with better resolving rate.
Pengcheng Wang, Liqun Ai, Yungang Li, Xiaoming Sang and Jinglong Bu
Y. J. Jin et al., "Effects of Metallic Ions on Photoluminescence Properties of CdSe/PAMAM Nanocomposites and their Application in Fingerprint Detection", Advanced Materials Research, Vols. 295-297, pp. 900-906, 2011