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Issue 24, 2017
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Metal-free branched alkyl tetrathienoacene (TTAR)-based sensitizers for high-performance dye-sensitized solar cells

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Abstract

A new series of metal-free alkylated tetrathienoacene (TTAR)-based organic chromophores, TPA–TTAR–TA (R = branched-C8H17, 1, TTAR-b8; R = C15H31, 2, TTAR-15; R = C9H19, 3, TTAR-9), are synthesized for application in dye-sensitized solar cells (DSSCs). Due to the extensively conjugated TTAR π-bridge, all three dyes exhibit high extinction coefficients (1 × 105 M−1 cm−1). By systematically exploring the effects of the TTAR alkyl chain substituents, a significant influence of the dye coverage (orientation) on the TiO2 surfaces is observed. The branched-alkyl TTAR-b8 (1) promotes significant tilting and packing distortion on TiO2 in comparison to more ordered monolayers of linear long alkyls TTAR-15 (2) and TTAR-9 (3). Photophysical measurements on the dye-grafted TiO2 films reveal that the branched-alkylated TTA unit in 1 enhances the electron injection efficiency, in agreement with the high quantum efficiency. Notably, by utilizing a three-dimensional (3D) photonic crystal (PhC) layer to enhance the coherent scattering an increase the light absorption, TTAR-b8 exhibits higher short-circuit current densities and achieved a high PCE of 11.18%. TTAR-b8 is thus the best performing fused-thiophene-based organic DSSC dye reported to date.

Graphical abstract: Metal-free branched alkyl tetrathienoacene (TTAR)-based sensitizers for high-performance dye-sensitized solar cells

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Publication details

The article was received on 28 Feb 2017, accepted on 26 Apr 2017 and first published on 27 Apr 2017


Article type: Paper
DOI: 10.1039/C7TA01825H
Citation: J. Mater. Chem. A, 2017,5, 12310-12321
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    Metal-free branched alkyl tetrathienoacene (TTAR)-based sensitizers for high-performance dye-sensitized solar cells

    Y. Ezhumalai, B. Lee, M. Fan, B. Harutyunyan, K. Prabakaran, C. Lee, S. H. Chang, J. Ni, S. Vegiraju, P. Priyanka, Y. Wu, C. Liu, S. Yau, J. T. Lin, C. Wu, M. J. Bedzyk, R. P. H. Chang, M. Chen, K. Ho and T. J. Marks, J. Mater. Chem. A, 2017, 5, 12310
    DOI: 10.1039/C7TA01825H

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