Preparation of Nanoparticle Coatings on Surfaces of Complex Geometry

Layer-by-layer sequential adsorption technique (LBL) can be utilized as a deposition method for nanostructured coatings on highly curved micrometer to millimeter scale surfaces, which is demonstrated in this work on a model films of strongly luminescent CdTe nanoparticles. Unlike LBL on colloids and flat surfaces, such procedure opens the door for the preparation of conformal nanostructured coatings for a variety of photonics and lab-on-the chip devices with predictable technological importance. Confocal microscopy data showed that prepared CdTe/PDDA coatings were found to be uniform and continuous. Strong coupling of the nanoparticle luminescence into the optical fiber attributed to high refractive index of CdTe/PDDA composite was obtained. As applied to nanoparticle coatings, two unanticipated effects were observed: (1) gradual red shift of the luminescence spectrum as the layer thickness increases; (2) two-stage luminescence transient including the significant enhancement of the luminescence during first 100 min of UV illumination. Similar results were obtained for the coatings made in the glass tube interior, which can be considered as simple models of microfluidic devices with channels of complex geometry.