In OLEDs, improved efficiency is obtained by compounds which can form inter alia electron injection layers of the formula (I)
wherein
R
1
is a 1-5 ring aryl (including polycyclic), aralkyl or heteroaryl group which is optionally substituted with one or more C
1
-C
4
alkyl, alkoxy or cyano;
R
2
and R
3
together form a 1-5 ring aryl (including polycyclic), aralkyl or heteroaryl group which is optionally substituted with C
1
-C
4
alkyl, alkoxy or cyano;
R
4
is hydrogen, C
1
-C
4
alkyl or aryl; and
Ar is monocyclic, bicyclic or tricyclic aryl or heteroaryl which is optionally substituted with one or more C
1
-C
4
-alkyl or alkoxy groups,
or an oligomer thereof.
在OLED中,通过化合物(I)形成可以形成电子注入层的改进效率,其中R1是1-5环芳基(包括多环),芳基烷基或杂环芳基基团,可以选择地用一个或多个C1-C4烷基,烷氧基或
氰基取代;R2和R3共同形成1-5环芳基(包括多环),芳基烷基或杂环芳基基团,可以选择地用C1-C4烷基,烷氧基或
氰基取代;R4是氢,C1-C4烷基或芳基;Ar是单环、双环或
三环芳基或杂环芳基,可以选择地用一个或多个C1-C4烷基或烷氧基取代,或其寡聚物。