Some substituted biaryl ring systems may be useful in light-emitting devices, such as those comprising a light-emitting diode. For example, substituted bipyridinyl or substituted phenylpyridinyl may be useful in these devices. The substituted biaryl ring system may have at least two different substituents, including one on each ring on the biaryl system. The first substituent may include optionally substituted carbazolyl, optionally substituted diphenylamine, optionally substituted diphenylaminophenyl, and optionally substituted carbazolylphenyl. The second substituent may include optionally substituted benzimidazol-2-yl, optionally substituted benzoxazol-2-yl, and an optionally substituted benzothiazol-2-yl.