Synthesis、Characterization and Simulation of Novel Carbazole Derivative Organic Dyes
Date Issued
2011
Date
2011
Author(s)
Wen, Shan-Ni
Abstract
A series of new organic dyes, 2-cyano-3-(5-(7-(5-(9-ethyl-9H-carbazol-3-yl) thiophen-2-yl)benzo[c][1,2,5]thiadiazol-4-yl)thiophen-2-yl)acrylic acid (NW), 3-(5- (7-(5-(9H-carbazol-9-yl)thiophen-2-yl)benzo[c][1,2,5]thiadiazol-4-yl)thiophen-2-yl)-2-cyanoacrylic acid (NHW), 2-cyano-3-(5-(7-(5''-(9-ethyl-9H-carbazol-3-yl) -3''-hexyl -2,2''-bithiophen-5-yl)benzo[c][1,2,5]thiadiazol-4-yl)thiophen-2-yl)acrylic acid (NS) and 3-(5-(7-(5''-(9H-carbazol-9-yl)-3''-hexyl-2,2''-bithiophen 5-yl)benzo[c][1,2,5] thiadiazol-4-yl)thiophen-2-yl)-2-cyanoacrylic acid (NHS), were designed and synthesized based on the structure of donor-π bridge-acceptor. Herein, carbazole, benzothiadiazole and cyanoacetic acid were used as donor, acceptor and anchoring group, respectively, in these dye molecules. All intermediates and final products were fully characterized using 1H-NMR, 13C-NMR and ESI mass. UV-vis spectrometer was employed to measure the extinction coefficient, absorption spectrum, and optical bandgap of N series organic dyes. The energy levels of HOMO and LUMO were also determined by cyclic voltammetry. Experimental results clearly indicated that the extension ofπ-conjugation length and the incorporation of carbazole as donor red-shifted the absorption spectrum and lowered the optical bandgap. Both NHW and NHS have similar conjugation length but the incorporation of carbazole in them had little effect on up-shifting the HOMO level. This is probably because carbazole is not a strong donor group. Moreover, comparing NW and NS showed the increment of conjugation length mainly down-shifted the LUMO level but kept HOMO almost unchanged, thus leading to the decrease in bandgap.
Additionally, the theoretical calculations of these dye molecules were performed in vacuum system. All the electronic absorption characteristics and HOMO, LUMO energy level were calculated by TD-DFT- B3LYP/ 6-31G / + / (d ) level of theory. We
V
can get the optimized structure and molecular orbital about electron distribution condition of the ground state and exicted state. The calculated HOMO level would be raised by inducing donor and extending the conjugation length. The absorption spectrum is in consistent with the experiment data.
Subjects
organic dyes
dye-sensitized solar cells
carbazole
benzothiadiazole
density functional theory (DFT)
time-dependent density functional theory (TD-DFT)
Type
thesis
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