Tunable morphology of the self-assembled organic microcrystals for the efficient laser optical resonator by molecular modulation.

Organic single-crystalline micro/nanostructures can effectively generate and carry photons due to their smooth morphologies, high photoluminescence quantum efficiency, and minimized defects density and therefore are potentially ideal building blocks for the optical circuits in the next generation of miniaturized optoelectronics. However, the tailor-made organic molecules can be generally obtained by organic synthesis, ensuring that the organic molecules aggregate in a specific form and generate micro/nanostructures with desirable morphology and therefore act as the efficient laser optical resonator remains a great challenge. Here, the molecular modulation of the morphology on the laser optical resonator properties has been investigated through the preparation of the elongated hexagonal microplates (PHMs) and the rectangular microplates (ORMs), respectively, from two model isomeric organic molecules of 1,4-bis(4-methylstyryl)benzene (p-MSB) and 1,4-bis(2-methylstyryl)benzene (o-MSB). Significantly, fluorescence resonance phenomenon was only observed in the individual ORM other than the PHM. It indicates that the rectangular resonators possess better light-confinement property over the elongated hexagonal resonators. More importantly, optically pumped lasing action was observed in the o-MSB rectangular morphology microplates resonator with a high Q ≈ 1500 above a threshold of ∼540 nJ/cm(2). The excellent optical properties of these microstructures are associated with the morphology, which can be precisely modulated by the organic molecular structure. These self-assembled organic microplates with different morphologies can contribute to the distinct functionality of photonics elements in the integrated optical circuits at micro/nanoscale.