Fundamental photophysical concepts and key structural factors for the design of BODIPY-based tunable lasers

This review aims to highlight the most recent and remarkable advances in our laboratory in designing efficient and long-lasting tunable dye lasers from the visible green region to the far-red-NIR edge. In recent years, we have synthesised, characterised, and applied a set of organic molecules covering this spectral region. The well-known BODIPY dye was selected as the photoactive scaffold owing to its rich and versatile chemistry. This modern dye allows deep and selective functionalization, which in turn modulates its photophysical properties. A deep understanding of the interplay between the molecular structure and photonic performance, as well as the unravelling of the key underlying photophysical mechanisms, is essential for designing photoactive dyes endowed with improved laser performance, outperforming the corresponding commercially available dyes in each spectral region. The design was focused on the chemical modification of the boron-dipyrrin core, as well as on the combination of dissimilar BODIPYs into a single molecular structure. Indeed, these complex and challenging multichromophoric assemblies exemplify a new generation of laser dyes with enhanced photonic performance. Following that, we provide an overview of the main structural and photophysical guidelines governing laser performance.