Organic semiconductors are of current interest in photonic applications, owing to their large optical cross-sections (absorption, emission, etc.) and broad spectral tunability. Optically pumped organic lasers have been demonstrated in a variety of resonator geometries, such as microcavity, micro-ring, distributed feedback (DFB), and photonic bandgap structures. However, electrically driven organic lasers remain a grand challenge, partially due to the high lasing-threshold observed so far. Therefore, development of organic gain materials with optimized energy levels that help decrease the lasing threshold is of crucial importance.

As a critical component of a laser, an optical microcavity provides feedback for light amplification, and defines the spatial and spectral coherence of the laser beam. Over the past decades, the fabrication technology for optical microcavities advanced significantly, but it still requires complicated, high-temperature, and costly production processes. Small molecule organic semiconductor materials offer an alternative bottom-up approach for fabrication of optical microcavities through the low-temperature solution-based self-assembly method. In this talk, I will present our research on the photonic performance of molecular micro- or nanostructures and the latest breakthroughs toward organic microlaser devices. Overall, the versatile features of organic materials are highlighted, because they bring tunable optical properties based on molecular design, size-dependent light confinement in low-dimensional structures, and various device geometries for nanophotonic integration.