Patent ID: 7186469

Claim:
An electroluminescent device comprising a first electrode, a second electrode, an electron transport layer, a hole transport layer, and a hole-blocking layer, wherein, (a) the hole-blocking layer is distinct from the electron transport layer, and (b) the hole-blocking layer comprises a compound of formula (I): wherein R 1 and R 2 are independently selected from the group consisting of an ethyl group, an n-propyl group, an isopropyl group, a n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an iso-pentyl group, a neopentyl group, a tert-pentyl group, a cyclopentyl group, a methylcyclopentyl group, a dimethylcyclopentyl group, a trimethylcyclopentyl group, a tetramethylcyclopentyl group, an n-hexyl group, a 2-ethylbutyl group, a 3,3-dimethylbutyl group, a cyclohexyl group, a methylcyclohexyl group, a dimethylcyclohexyl group, a trimethylcyclohexyl group, an ethylcyclohexyl group, a diethylcyclohexyl group, a triethylcyclohexyl group, a 2-ethylhexyl group, an n-nonyl group, an n-decyl group, an n-dodecyl group, an n-tetradecyl group, an n-hexadecyl group, a benzyl group, a phenethyl group, an α-methylbenzyl group, an α,α-dimethylbenzyl group, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a furfuryl group, a 2-methylbenzyl group, a 3-methylbenzyl group, a 4-methylbenzyl group, a 4-ethylbenzyl group, a 4-isopropylbenzyl group, a 4-tert-butylbenzyl group, a 4-n-hexylbenzyl group, a 4-nonylbenzyl group, and a 3,4-dimethylbenzyl group.