Cascaded organic electroluminescent device having connecting units with n-type and p-type organic layers

Abstract

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 OMEGA -cm.

Description

technical field

[0001] The present invention relates to providing a plurality of organic electroluminescent units to form a cascaded organic electroluminescent device. Background technique

[0002] Organic electroluminescent (EL) devices or organic light emitting (OLED) devices are electronic devices that emit light in response to an applied electrical potential. The structure of an OLED includes an anode, an organic EL medium, and a cathode in sequence. An organic EL medium located between an anode and a cathode usually consists of an organic hole transport layer (HTL) and an organic electron transport layer (ETL). The holes and electrons recombine in the ETL near the HTL / ETL interface and emit light. Tang et al. ["Organic Electroluminescent Diodes", Applied Physics Letters, 51, 913 (1987), and co-cited US-A-4,769,292] demonstrated very high efficiencies in OLEDs employing the layer structure described above. Various OLEDs with alternating layer structures have subsequen...

Images