A cascaded organic electroluminescent device includes an anode and a cathode. The device also includes a plurality of organic electroluminescent units disposed between the anode and the cathode, wherein the organic electroluminescent units comprise at least a hole-transporting layer, an electron-transporting layer, and an electroluminescent zone formed between the hole-transporting layer and the electron-transporting layer wherein the physical spacing between adjacent electroluminescent zones is more than 90 nm; and a connecting unit disposed between each adjacent organic electroluminescent unit, wherein the connecting unit comprises, in sequence, an n-type doped organic layer and a p-type doped organic layer forming a transparent p-n junction structure wherein the resistivity of each of the doped layers is higher than 10 -cm.