Synthesis, photophysics, and electroluminescence of poly(dibenzofluorene)s

A series of soluble poly(dibenzofluorene) derivatives that contain dibenzo[a,g]fluorene, dibenzo[a,i]fluorene, and dibenzo[c,g]fluorene repeat units in the main chain have been synthesized, characterized, and explored as emissive materials in polymer light emitting diodes (PLEDs). These polymers possess higher glass transition temperatures (108-133 °C) than that of poly(2,7-(9,9-dialkyl)fluorene) (PFO). The photophysical and electrochemical properties of these polymers are affected by the steric hindrance effect. These polymers emit blue light in dilute solution (378-400 nm) and in the solid state (426-447 nm). As emissive materials in PLEDs, blue electroluminescence with a brightness of up to 3130 cd m^-2 is obtained from single-layer diodes of P₂ with aluminum/barium in air.