1. A compound comprising one or more groups of Formula A: where M is selected from sulfur (S), oxygen (O), selenium (Se), tellurium (Te), —N(R 6 )—, —C(R 7 ) 2 —C(R 8 ) 2 —, —CR 7 ═CR 8 —, —S(═O) 2 —, —S(═O)—, —C(═O)—, —C(═S)—, or —C(═N—R 1 )—; where R 6 is H or a substituent; R 7 is H or a substituent; R 8 is H or a substituent; and X 1 is N or C—R 9 , Y 1 is N or C—R 9 , and one of X 1 and Y 1 is N, and the other is C—R 9 ; where R 9 is F, Cl, Br, or I.