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

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-biphenyl-4-4'-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 lm W-1 (14.7 cd A(-1); EQE: 7.2%) to 17.1 lm 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.