A dye compound is described, which is expressed by formula (I):
wherein A
1
, A
2
and A
3
each independently represent a substituted or unsubstituted 1,4-phenylene or 2,5-thiophene group, and B
1
and B
2
each independently represent a substituted or unsubstituted aryl group. The dye compound is suitably used as a dye sensitizer in a dye sensitized solar cell (DSSC).