Patent ID: 7811676

Claim:
An electroluminescent device which comprises: (i) a first electrode which functions as an anode; (ii) a second electrode which functions as a cathode; and, (iii) between said first and second electrodes, the following layers (a) to (e) in sequence: (a) a layer of a hole transport material; (b) a first layer comprising a first electroluminescent metal complex or a first electroluminescent organometallic complex having a band gap; (c) a layer comprising a second electroluminescent metal complex or a second electroluminescent organometallic complex having a band gap, wherein the band gap of the second complex is larger than that of the first complex and wherein the highest occupied molecular orbital (HOMO) of the first complex is higher, and the lowest unoccupied molecular orbital (LUMO) of the first complex is lower, than those of the second complex, and wherein the layer of second complex has a thickness of about 10 nm or less; (d) a second layer comprising the first complex; and, (e) a layer of an electron transport material; and, further wherein the second electroluminescent metal complex or second electroluminescent organometallic complex emits light in the ultraviolet region of the spectrum.