A compound according to various embodiments of the present invention is expressed by chemical formula 1 below. In chemical formula 1, X is O or S; R1 and R2 each are independently selected from the group consisting of aryl, heteroaryl, and -P(O)-R3R4; and the aryl, heteroaryl, and -P(O)-R3R4 are substituted or unsubstituted with one to four substituents selected from the group consisting of (C1-C4)alkyl, (C1-C4)alkoxy, aryl, and heteroaryl, wherein the "aryl" means a 6- to 10-membered group, the "heteroaryl" means a 5- to 14-membered group having one to four heteroatoms selected from oxygen, sulfur, and nitrogen (including quaternary nitrogen), and R3 and R4 each are independently selected from aryl or heteroaryl.
