In some embodiments of interest, Y is a fluorenylidenyl group and R3 is a bond between Y and the carbon atom adjacent to Y. In some embodiments of interest, Y is an arylamine group, such as an (N,N-disubstituted)arylamine group (e.g., triarylamine group, alkyldiarylamine group, and dialkylarylamine group), a carbazolyl group, and a julolidinyl group.