Real-Time Tunable Red/Near-Infrared Solid-State Emitters in the First Biological Window: 9,9-Diethyl-2-diphenylaminofluorene-Based Push-Pull Fluorophores for Distributed Feedback and Random Lasing Applications

In biological imaging, red-to-infrared emissive dyes facilitate direct visualization of molecular interactions, through deep tissue penetration, along with minimal tissue damage. This work uses simple systems based on a single dye-doped polymeric thin film for distributed feedback and random lasing investigations. As active compounds, novel push-pull luminescent diphenylaminofluorene derivatives are used, functionalized with different acceptor groups. Integration of such luminescent dyes with a transparent polymeric medium allows fabrication of real-time lasing tunability in the first biological window (650-950 nm). The observed spectral tuning of 150 nm is a groundbreaking value obtained in a single-dye system.