Two-dimensional arrangement of monodisperse ZnO particles with Langmuir–Blodgett technique

Monodisperse, spherical ZnO particles with different sizes were synthesized in diethylene glycol. Particles were characterized by means of TEM and SEM images, XRD, nitrogen adsorption–desorption isotherms and small angle X-ray scattering methods. The ZnO nanoparticles were used to prepare Langmuir-films (at the air/water interface) and Langmuir–Blodgett films (on solid supports). Langmuir-films were characterized by surface pressure vs. surface area isotherms. Single and multilayer Langmuir–Blodgett films were prepared for optical interference, photonic band gap and photoluminescence investigation. We improved our previous optical interference model, special features of ordered films of uniform spherical particles were integrated into the model to calculate effective refractive index and thickness of the films. Photonic band gap of single layer was determined from transmittance spectra and film parameters were calculated such as effective refractive index of the film and volume fraction of partilces in the film. Photoluminescence measurements showed correspondence between primary crystallite size of particles and the wavelength of photoluminescence emission maxima.