Azadipyrromethene-Based Conjugated Oligomers with Near-IR Absorption and High Electron Affinity

Solution-processable conjugated oligomers incorporating red-light absorbing azadipyrromethenes (aza-DIPY) within the main chain were synthesized via palladium-catalyzed Sonogashira coupling reactions. Thin films of these compounds absorbed light up to similar to 1000 nm and displayed reversible reductions as ascertained by cyclic voltammetry experiments. Reactions with trifluoroboron etherate yielded materials displaying a unique combination of good solubility in organic solvents, low optical band gaps (similar to 1.3 eV), and high electron affinity (similar to 4.5 eV).