Light-emitting conjugated polymers polyfluorene

Abstract Poly(dibenzosilole)s are an emerging class of polymers with similar optoelectronic properties to polyfluorenes. With increased stability towards oxidation, several poly(dibenzosilole)-based devices, such as light emitting diodes, have shown improved performance over their polyfluorene counterparts. As a consequence of reduced conjugation in the polymer chain, some poly(dibenzosilole)s have high triplet excited state energies, which make them suitable hosts for blue triplet emitters in electrophosphores-cent devices. 

Polyfluorene is one of the most attractive conjugated polymers for application in light-emitting devices [36-38], It is characterized by low electron affinity and, in consequence, several authors have inserted electron-deficient moieties into the aromatic chain to modify the position of the frontier orbital and increase the electron affinity in order to achieve a better balanced hole and electron injection in electroluminescent diodes. Among the electron-deficient groups, thienyl-5,5-dioxide and dibenzothienyl-5,5-dioxide have also been employed [16-18, 20-25, 27, 28],... 

The various functional layers in PLED devices are outlined in Figure 10.14. By applying a voltage across the device, electrons and holes are injected into the photoluminescent polymer, where they recombine to form excitons and emit light. Suitable, commonly used emissive polymers are conjugated materials such as poly(phenylenevinylene)s (PPVs) and polyfluorenes. 

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