Directed assembly of semiconductor nanorods using polymers

The ability to assemble nanoparticles into predefined structure is crucial for fabricating many advanced devices. The goal of this study is to explore the creation of novel complex superstructures of semiconductor nanorods and to get better control over their orientation utilizing polymers. Polymers provide a versatile platform for dispersing nanoparticles. Additionally, different polymers seldom mix, therefore combination of different polymers necessarily gives rise to structured materials.

Controlling the orientation angle of quantum rods (QRs) with respect to the substrate is decisive for intensifying their emission. Theoretical calculations show that aligning the quantum rods parallel to the substrate concentrates more of the emission in the direction normal to the substrate, which is important for achieving high brightness displays. The main idea is to utilize the tendency of nanorods to segregate to the film interfaces and align parallel to them. The design involves alternating polystyrene (PS) and poly(2-vinyl pyridine) (P2VP) layers, in which CdSe@CdS quantum rods are dispersed in the PS layers and segregate to their interfaces. The effect of QR filling fraction and number and thickness of layers on the strength and directionality of emission is studied.