Application of a Novel Fullerene-Containing Copolymer to Electroluminescent Devices

The optical properties of a soluble fullerene (C 60 )-containing copolymer, (PS) x C 60 (PMMA) y, were investigated. We employed the (PS) x C 60 (PMMA) y in a polymer electroluminescent device as a hole-injecting layer. The forward-biased ITO/poly[2-methoxy-5-(2‘-ethyl-hexyloxy)-1,4-phenylenevinylene]/(PS) x C 60 (PMMA) y /Al device showed strongly quenched electroluminescence. In contrast, when the device was operated in reverse-bias direction, the luminescence and the yield were enhanced. The turn-on voltage of the reverse-biased device was −2.6 V. The quantum efficiency and the emitted light power were improved by ≈5 and ≈20 times, respectively, compared with those of the single-layer device.