Investigation of new carbazole based metal-free dyes as active photo-sensitizers/co-sensitizers for DSSCs

Abstract

Herein, we report the molecular design, synthesis and characterization of three new D-D-?-A configured metal-free chromophores D<inf>1-3</inf> for their application in DSSCs as sensitizers as well as co-sensitizers. The new entities comprise carbazole as donor scaffold, 4-methoxyphenyl group as auxiliary donor and three different units, viz. cyanoacetic acid, 2, 4-thiazolidinedione and barbituric acid as acceptor/anchoring groups. Their photochemical, electrochemical and theoretical studies were carried out in order to assess their feasibility as active sensitizers. Further, D<inf>1-3</inf> were exploited as co-sensitizers along with NCSU-10 dye. Their photoelectrochemical performances and charge transport properties in fabricated DSSCs were studied. The results revealed that D<inf>1</inf> sensitizer displayed the highest PCE of 2.20% among the three dyes. D<inf>3</inf> when co-sensitized with NCSU-10 displayed an improved PCE of 8.32% (J<inf>SC</inf> = 19.25 mA.cm?2, V<inf>OC</inf> = 0.680 V, FF = 63.7%) while NCSU-10 alone exhibited PCE of 8.25% (J<inf>SC</inf> = 20.41 mA.cm?2, V<inf>OC</inf> = 0.667 V, FF = 60.6%). © 2017 Elsevier Ltd