Discovery of tunable and soluble organic emitters for solid-state lasers with a self-driving laboratory

We have recently demonstrated the ability of using self-driving laboratories for AI-driven searches of organic emitters for solid-state lasing devices. Our past workflow featured solubility challenges for such large molecular moieties. In this next-generation study, we return to the drawing board to explore a family of compounds that are much solution processable and composed of a set of electronic cores that provide a broader color response. Out of 252 potential candidates, and with guidance from DFT calculations, we selectively perform a comprehensive study exploring 51 fluorene-based A-B-A-type organic laser oligomers, armed with our self-driving lab. The candidates range from simple hydrocarbon molecules to complex heteroatom-mixed molecules. As a result of this study, we highlight diketopyrrolopyrrole and benzodiazole derivatives for their largely red-shifted emissions. Furthermore, we investigate the effect of color change arising from heteroatom permutation, fluorine addition, thiophene coupling, and a combination of fluorine addition and thiophene coupling. Amplified spontaneous emission (ASE) measurements in the solid state further corroborate the lasing potential of selected candidates, reinforcing their suitability for future device applications. The computational study with density functional theory confirms the experimental results.