Synthesis and characterization of simple trans-AB-porphyrins for dye-sensitized solar cells

Four simple trans-AB-porphyrins 3a–3d either without any alkoxyl substituent, or with a mono-alkoxyl chain at different (ortho and para) positions of the meso-phenyl ring, or with two alkoxyl chains at two ortho positions of the meso-phenyl ring were designed and synthesized via three steps. The synthesis is simple and no expensive metal catalyst is involved. All compounds were characterized by 1H-NMR and mass spectraometry. UV-Vis absorption spectra and B band-excited fluorescence emission spectra were also obtained. The synthesized porphyrins were applied in dye-sensitized solar cells (DSSCs). Up to 3.05% conversion efficiency was realized for 3d under our experimental conditions, attributed to the two long alkoxyl chains present at the ortho positions of the meso-phenyl group. The influences of the position and the number of the alkoxyl chains at the macrocyclic meso-phenyl group on the photovoltaic performance of DSSCs are well explained via DFT calculations. It was shown that the VOC and JSC of the sensitizers are determined by μnormal, ΔGinject and LHE.