The present invention relates to an. organic semiconductive layer which is an electron transport layer and/or an electron injection layer and/or an n-type charge generation layer, the organic semiconductive layer comprising at least one compound of formula (1) wherein R1 and R2 are each independently selected from C1 to C16 alkyl; Ar1 is selected from C6 to C14 arylene or C3 to C12 heteroarylene; Ar2 is independently selected from C14 to C40 arylene or C8 to C40 heteroarylene; R3 is independently selected from H, C1 to C12 alkyl or C10 to C20 aryl; wherein each of Ar1, Ar2 and R3 may each independently be unsubstituted or substituted with at least one C1 to C12 alky group; n is 0 or 1; and m is 1 in case of n=0; and m is 1 or 2 in case of n=1, phosphine oxide compounds comprised therein and to organic electroluminescent devices comprising such layers and compounds.