Layer-by-layer assembled films of nanoparticles: materials perspectives and photonics and biophotonics applications

The layer-by-layer assembly (LBL) of hybrid polyelectrolyte/nanoparticle thin films and the structural features of thin film prepared by it are discussed. The areas of applications, which are currently considered for LBL assemblies include photovoltaics, light-emitting diodes, high-density magnetic memory, non-linear optical switches, nanoscale interconnects, resist layer, sensors, gas separation membranes, optical filters, and others. This technique is quite simple and based on the sequential adsorption of alternating (mono)layers of oppositely charged inorganic colloids and polyelectrolytes and results in composite materials combining mechanical properties of polymers and unique physical characteristics of nanosized inorganic clusters. The nanoparticles are made prior to the assembly, and therefore, allow for the accurate control over their size and size distribution.