In this work, four free metal-organic dyes were synthesized as a donor-π bridge-acceptor system in a one-pot condensation reaction and were used as sensitizers in DSSCs.To explore the effect of substituents of the efficiency of the DSSCs, three different types of substituents were applied at the -NH position on the imidazole ring: nitrobenzene, alkyl chain and phenyl coded (PP2, PP3 and, PP4) resp...