A photosensitizer dye is provided. The photosensitizer dye is a Ru complex as formula (1):
wherein X
1
represents one of formula (2)˜(18) and X
2
represents hydrogen atom or X
1
and X
2
both represent one of formula (2)˜(18),
wherein Z
1
represents one of formula (35)˜(41) and Z
2
represents hydrogen atom or one of formula (35)˜(41) or a group the same with Z
1
.