Fabricating transparent multilayers with UV and near-IR double-blocking properties through layer-by-layer assembly

We have fabricated a transparent composite film with UV and near-infrared (near-IR) double-blocking properties using polyethyleneimine (PEI), indium tin oxide (ITO), and zinc oxide (ZnO) through layer-by-layer (LbL) assembly under an ultrasonic field. By applying ultrasonic-assisted LbL assembly, the aggregation of nanoparticles has been excluded, resulting in a flatter and more transparent (visible range) film than that obtained under conventional LbL assembly. Moreover, the effects of the ultrasonic field are discussed in terms of the fact that the transformation between the states of PEI/ITO films assembled with or without ultrasonic field was reversible. To enhance the UV blocking properties in the most damaging region (290-350 nm), we incorporated ZnO nanoparticles, which can block UV rays below 350 nm, and the obtained hybrid multilayer displayed a high transparency of over 85% (visible range) and good UV-/near-IR double-blocking effects that shielded nearly 80% of the UV rays under 350 nm and 80% of the IR radiation above 1600 nm.