The Effect of Keto Defect Sites on the Emission Properties of Polyfluorene-Type Materials

Keto defect sites play a key role as the source of low-energy emission bands in polyfluorene type materials. The formation of fluorenone defect sites can be regarded as a dominant degradation mechanism in light-emitting devices based on polyfluorenes. The superiority of difunctionalization (see Figure) at the methylene group in –CR2– bridged polyphenylene and polyarylene derivatives is illustrated.