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Issue 5, 2017
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Heteroleptic Ru(II) cyclometalated complexes derived from benzimidazole-phenyl carbene ligands for dye-sensitized solar cells: an experimental and theoretical approach

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Abstract

We have designed and synthesized two new ligands based on N-heteroleptic/phenyl carbene (NH-phenyl C) i.e., 1-benzyl-2-(3,5-bis(trifluoromethyl)phenyl)-1H-benzo[d]imidazole (L1) and 3-(1-benzyl-1H-benzol-2-yl)-10-hexyl-10-H-phenothiazene (L2), used as ancillary ligands to heteroleptic Ru(II) complexes for dye-sensitized solar cells. Both NCS groups of the N719 sensitizer are replaced with L1 (TC-1) and L2 (TC-3) to obtain cyclometalated Ru(II) complexes and one of 4,4′-dicarboxylato-2,2′-bipyridine (dcbpy) with L1 to obtain a heteroleptic Ru(II) complex (TC-2). The presence of two trifluoromethyl groups of the L1 ligand stabilizes the HOMO level of Ru(II) complexes and the presence of a phenothiazine moiety of the L2 ligand alters the absorption properties of the TC-3 complex. Both the ligands and the heteroleptic Ru(II) complexes are characterized by elemental analyses, ESI-MS, 1H NMR, absorption and emission spectroscopy as well as electrochemical methods. The absorption spectra of TC-1 and TC-3 are blue shifted, when compared to the standard N719 sensitizer. The assessment of these newly designed cyclometalated and heteroleptic Ru(II) complexes has revealed that TC-2 exhibits an efficiency of 7.63%, whereas TC-1 has an efficiency of 6.39% using an I/I3 redox couple. DFT and nanosecond transient absorption kinetic studies have been adopted to understand the low efficiency of the TC-3 complex.

Graphical abstract: Heteroleptic Ru(ii) cyclometalated complexes derived from benzimidazole-phenyl carbene ligands for dye-sensitized solar cells: an experimental and theoretical approach

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Publication details

The article was received on 13 Oct 2016, accepted on 16 Nov 2016 and first published on 14 Dec 2016


Article type: Research Article
DOI: 10.1039/C6QM00264A
Citation: Mater. Chem. Front., 2017,1, 947-957
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    Heteroleptic Ru(II) cyclometalated complexes derived from benzimidazole-phenyl carbene ligands for dye-sensitized solar cells: an experimental and theoretical approach

    T. Jella, M. Srikanth, Y. Soujanya, S. P. Singh, L. Giribabu, A. Islam, L. Han, I. Bedja and R. K. Gupta, Mater. Chem. Front., 2017, 1, 947
    DOI: 10.1039/C6QM00264A

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