Self-assembly and optical properties of water-soluble porphyrin alternating CdSe nanoparticulate films

A new type of self-assembled film was prepared by alternating deposition of oppositely charged meso-tetra-(4-trimethylaminophenyl) porphyrin nickel iodide (NiTAPPI) and citrate-stabilized CdSe nanoparticles. The stepwise deposition process was monitored by means of UV–vis spectroscopy. The interaction between the porphyrin and CdSe nanoparticles was characterized with UV–vis and fluorescence spectra. The SEM images showed the formation of densely packed two-dimensional array and the conversion of disorder-to-order of CdSe nanoparticles on the quartz substrate modified by PDDA when depositing positively charged NiTAPPI. The self-assembled film placed in ambient air exhibited significant enhancement of fluorescence intensity. The effects of heat treatment and UV-light irradiating on fluorescence properties of the composite films were investigated in details.