Patent ID: 7494722

Claim:
A tandem OLED comprising: a) an anode; b) a cathode; c) at least two electroluminescent units disposed between the anode and the cathode, wherein each of the electroluminescent units includes at least one hole-transporting layer and one organic light-emitting layer; d) an intermediate connector disposed between adjacent electroluminescent units, wherein the intermediate connector includes an n-doped organic layer and an electron-accepting layer being disposed closer to the cathode than the n-doped organic layer, wherein the electron-accepting layer has a thickness range of from 3 nm to 100 nm and having one organic material having a molecular weight greater than 350, and having a reduction potential greater than −0.5 V vs. a Saturated Calomel Electrode, and wherein the n-doped organic layer is in direct contact with the electron-accepting layer; and e) the material in the electron-accepting layer consists of a chemical compound of the following formula: wherein R 1 -R 6 represent hydrogen or a substituent independently selected from the group including halo, nitrile (—CN), nitro (—NO 2 ), sulfonyl (—SO 2 R), sulfoxide (—SOR), trifluoromethyl (—CF 3 ), ester (—CO—OR), amide (—CO—NHR or —CO—NRR′), substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, and substituted or unsubstituted alkyl, where R and R′ include substituted or unsubstituted alkyl or aryl; or wherein R 1 and R 2 , R 3 and R 4 , or R 5 , and R 6 combine form a ring structure including an aromatic ring, a heteroaromatic ring, or a nonaromatic ring, and each ring is substituted or unsubstituted.