Electroluminescent device
View Patent ↗An OLED device comprises a cathode and an anode and has located therebetween a light-emitting layer comprising a phosphorescent light-emitting material and a host comprising a compound of a tetravalent atom wherein the four groups bonded to the atom are aromatic rings, at least one of which contains an electron-withdrawing group (EWG) substituent comprising at least three atoms, the compound having a triplet energy of at least 2.7 eV and a LUMO energy within 0.6 eV of the LUMO energy of at least one material in an adjacent layer on the cathode side of the light-emitting layer. Particular embodiments include certain tetravalent silicon compounds. The light-emitting layer emits blue light and provides good luminance and reduced drive voltage.
1. An OLED device comprising a cathode and an anode and having located therebetween a light-emitting layer comprising a phosphorescent light-emitting material and a host comprising a compound of Formula (3a):
wherein:
s, t, u, and v are independently 0-5, provided that s, t, u, and v are not all 0; and
each r 1 through r 4 represents an independently selected substituent, provided at least one r 1 through r 4 comprises a substituent of Formula (3b):
wherein:
each Ar 1 may be the same or different and each represents an independently selected aromatic group.
2. An OLED device of claim 1 wherein s, t and u are 0 and v is 1.
3. An OLED device of claim 1 wherein the compound of Formula (3a) is:
4. The device of claim 1 wherein a compound of Formula (3a) is present in a layer adjacent to the light-emitting layer on the cathode side.
5. An OLED device comprising a cathode and an anode and having located therebetween a light-emitting layer comprising a phosphorescent light-emitting material and a host comprising a compound of Formula (3c):
wherein:
s, t, u, and v are independently 0-5, provided that s, t, u, and v are not all 0; and
each r 5 through r 8 represents an independently selected substituent, provided at least one r 1 through r 4 comprises a substituent of Formula (3d):
wherein:
each A 2 may be the same of different and each represents an independently selected aromatic group.
6. An OLED device of claim 5 wherein s, t and u are 0 and v is 1.
7. An OLED device of claim 5 wherein the compound of Formula (3c) is:
8. The device of claim 5 wherein a compound of Formula (3c) is present in a layer adjacent to the light-emitting layer on the cathode side.