Dear Emam,

This is very general question.

the answer strongly depend on your facilities and your Institute financial limits.

I think after these consideration at the first step, It is better to start by reading a complete review articles about DSSC ( for example http://pubs.acs.org/doi/abs/10.1021/cr900356p?journalCode=chreay

)

bests

Dear Eman,

Any dye you can use by considering following requirements

1. dye should contain specific anchoring groups for adsorption on metal oxide surface.

2. HOMO and LUMO levels of dye should adjust according to the band edge levels of semiconductor and electrolyte.

3. Dye should absorb light in visible and near IR regions.

By compromising above conditions, you can use any dyes.

Commonly used dyes are N 719, N3 and black dye theae Ru metal based dyes. Metal free dyes are also can be used. You can find more information in literature.

There are different approach applied for choosing dyes:1) do you need it to be cost effective or environment friendly

2) do you need it to have high efficiency?

based on that you can choose the dye whether it should be natural or organic