Better than metallic nanoparticles and quantum dots? While in metallic and semiconductor nanoparticles the crystal structures are defined by the nature of materials and do not vary significantly within a given material, in organic (molecular) nanocrystals (ONCs) variations in molecular packings can be significant, resulting in polymorphs with different properties. Aromatic nanocrystals can be especially interesting as they may be very robust and have advantageous photonic and electronic properties. While inorganic nanocrystals cannot be easily disassembled to their molecular or atomic components, ONCs are prone to disassembly into molecular constituents (by dissolving in suitable organic solvents). This is a versatile property in terms of complete bottom-up self-assembly and re-assembly at the molecular level, facilitating diversity and recycling. But there is a problem with ONCs, and it is related to control and solubility. It is notoriously difficult to control the structure and morphology of ONCs and prevent their precipitation. In our lab we can address both challenges, employing our understanding of crystallization mechanisms. For example, we were able to make soluble and tunable ONCs having advantageous nonlinear optical properties (second harmonic generation), 2D soluble crystalline sheets that excel in light harvesting (transfer excitons over long distances), and more. We also develop bulk materials based on ONCs. These nanomaterials are based on simple aromatic molecules (robust perylene diimide dyes), possess high thermal stability and exhibit advantageous photonic and electronic properties. All these systems can be easily fabricated, disassembled, and recycled!
Rosenne, S; Grinvald, E; Shirman, E; Neeman, L; Dutta, S; Bar-Elli, O; Ben-Zvi, R; Oksenberg, E; Milko, P; Kalchenko, V; Weissman, H; Oron, D; Rybtchinski, B (2015). Self-Assembled Organic Nanocrystals with Strong Nonlinear Optical Response. Nano letters. 15:7232-7.
Shahar, C; Baram, J; Tidhar, Y; Weissman, H; Cohen, SR; Pinkas, I; Rybtchinski, B (2013). Self-Assembly of Light-Harvesting Crystalline Nanosheets in Aqueous Media. ACS Nano. 7:3547-3556.
