Nanodot-enhanced high-efficiency pure-white organic light-emitting diodes with mixed-host structures

Abstract

A relatively high-efficiency, fluorescent pure-white organic light-emitting diode was fabricated using a polysilicic acid (PSA) nanodot-embedded polymeric hole-transporting layer (HTL). The diode employed a mixed host in the single emissive layer, which comprised 0.5 wt % yellow 5,6,11,12-tetra- phenylnaphthacene doped in the mixed host of 50 % 2-(N,N-diphenyl-amino)-6-[4- (N,N-diphenylamino)styryl]naphthalene and 50 % N,N'-bis(1-naphthyl)-N,N'- diphenyl-1,10-biphenyl4-4'-diamine. By incorporating 7 wt % 3 nm PSA nanodot into the HTL of poly(3,4-ethylene-dioxythiophene)-poly-(styrenesulfonate), the efficiency at 100 cd m-2 was increased from 13.5 Im W ' (14.7 cd A-1; EQE: 7.2 %) to 17.1 Im W-1 (17.6 cd A-1; EQE: 8.3 %). The marked efficiency improvement may be attributed to the introduction of the PSA nanodot, leading to a better carrier-injection-balance. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA.