Controlling Nanorod Self-Assembly in Polymer Thin Films

The integration of functional polymers and semiconducting nanorods can lead to properties unattainable by either of the components independently. Elongated nanocrystals provide advantageous anisotropic physical properties which could be uniquely harnessed via integration into hybrid materials, if control over their orientation could be imposed. Controlling this orientation of anisotropic nanocrystals in polymer composites is challenging due to the presence of multiple interactions between the nanorods, polymer, and surfaces of the films. This study demonstrates a simple yet versatile method to obtain vertically aligned nanorod arrays in polymer composites over large areas. Comparison of systems consisting of rods of varying geometry and chemistry of ligand and/or polymer indicates that nanorod nanorod interactions dominate the self-assembly behavior of the nanocrystals, while weak polymer nanorod interactions can lead to independent co-self-assembly of each of the components in the system and allow for the incorporation of a wide variety of polymers with complementary functionality. Aligned nanorod composites can provide fundamental understanding of both the phase behavior and anisotropic electronic properties of nanorods in polymers. Incorporating functional polymers can enable the fabrication of efficient hybrid thin film devices for applications in photovoltaics, LEDs, and solar-fuel membranes.