Venkateswararao, A.A.VenkateswararaoJustin Thomas, K.R.K.R.Justin ThomasLee, C.-P.C.-P.LeeHo, K.-C.K.-C.HoKUO-CHUAN HO2018-09-102018-09-102015http://www.scopus.com/inward/record.url?eid=2-s2.0-84920436193&partnerID=MN8TOARShttp://scholars.lib.ntu.edu.tw/handle/123456789/391287Organic dyes containing 2-diphenylaminocarbazole donors and decorated with auxiliary chromophores at the diphenylamine moiety have been synthesized and characterized. The nature of the chromophores on diphenylamine unit alters the light-harvesting properties and HOMO/LUMO energies of the dyes. Butoxy substitution raises the HOMO and lowers the LUMO energies. But the incorporation of fluorenyl units fine-tunes the LUMO upwardly, which improves the thermodynamic driving force for electron injection into the conduction band of TiO2 and hikes the incident photon-to-current conversion efficiency. Consequently, a dye with fluorene in the donor unit and thiophene in the π-conjugation pathway is the most efficient (5.76%) and has the highest photocurrent density (14.60mAcm-2) in the series. Electrochemical impedance analysis of the devices showed the importance of fluorene units in suppressing electron recombination. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Carbazoles; Chromophores; Dye-sensitized solar cells; Electrochemical impedance spectroscopy; Organic dyes[SDGs]SDG7journal article10.1002/ajoc.201402235