Orthogonal conformation regulation enables highly efficient phosphorescence emission in BODIPY-fluorene derivatives without heavy atoms

The BODIPY-Fluorene derivatives with an orthogonal conformation were prepared for the emission of efficient phosphorescence. The derivatives show visible light absorption (497–513 nm), high phosphorescence quantum efficiency (36.2%) and realize control of luminescence color from green to orange-red. Typical orthogonal conformation and smaller excited state (S 1 and T 4 ) energy gap (0.05 eV) are favorable for intersystem crossing (ISC) process. The calculation are carried out for rationalization between the photophysical properties and conformation of the BODIPY-Fluorene derivatives. We demonstrate that the conformational substitution positions and the distance between D-A are promising strategy to regulate the emission lifetime and quantum efficiency for BODIPY derivatives. Moreover, the ability to generate singlet oxygen was measured by photooxidation of 1,3-diphenylisobenzofuran (DPBF) by singlet oxygen ( 1 O 2 ) photosensitization . At the same time, the LED device displays bright orange-red emission. This work paves the way for further research into the design and application of such materials in advanced optics.