New copolymers for applications as organic LEDs

Abstract

During the past five years, (pi) -conjugated organic polymers, such as poly[p-phenylene vinylene] (PPV) and polythiophenes, have become attractive alternatives to semiconducting materials as light-emitting diodes. Various approaches to tuning emission wavelength have been proposed, such as controlling the conjugation length by employing polymer oligomers or via steric effects in the fully conjugated polymers, or by using substituent effects to fine-tune the band gap. In the present study, we demonstrate that these features can be designed into copolymeric structures in which (pi) -conjugated emitters of carefully controlled length alternate with various non-emitting flexible spacers which improve solubility and thus processibility. These copolymers display predictable emission characteristics which can also be fine-tuned by incorporation of electronic substituent effects.