Aggregation induced light harvesting of molecularly engineered D-A-π-A carbazole dyes for dye-sensitized solar cells

[Display omitted] •Dyes with cyanopyridine auxiliary acceptor were synthesized.•J-aggregation leads to broader absorption spectra.•Aggregation assisted in better performance. Novel class of metal free organic dyes (CCTh and CCBz) with D-A-π-A configuration, having carbazole as donor and 3-cyanopyrid...

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Bibliographic Details
Published in:Solar energy 2018-11, Vol.174, p.1085-1096
Main Authors: Hemavathi, B., Jayadev, V., Pradhan, Sourava C., Gokul, G., Jagadish, Kusuma, Chandrashekara, G.K., Ramamurthy, Praveen C., Pai, Ranjith Krishna, Narayanan Unni, K.N., Ahipa, T.N., Soman, Suraj, Geetha Balakrishna, R.
Format: Article
Language:English
Subjects:
Absorption
Absorption spectra
Agglomeration
Anchoring
Carbazole
Carbazoles
Current carriers
Cyanopyridine
D-A-π-A
DSSC
Dye-sensitized solar cells
Dyes
Electrochemistry
Energy conversion efficiency
Gas absorption
Open circuit voltage
Photovoltaic cells
Photovoltaics
Solar cells
Solar energy
Spectroscopy
Titanium dioxide
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Summary:[Display omitted] •Dyes with cyanopyridine auxiliary acceptor were synthesized.•J-aggregation leads to broader absorption spectra.•Aggregation assisted in better performance. Novel class of metal free organic dyes (CCTh and CCBz) with D-A-π-A configuration, having carbazole as donor and 3-cyanopyridine as auxiliary acceptor replacing conventional benzannulated heterocycles along with variable π-linkers were synthesized and used in dye-sensitized solar cells (DSSCs). Both the dyes are having cyanoacrylic acid as the anchoring group with thiophene (CCTh) and phenylene (CCBz) as π-linkers. The photophysical, electrochemical, theoretical and photovoltaic properties of the dyes were investigated in detail. The absorption spectra of dyes on TiO2 showed broader absorption band for CCTh in comparison to the solution spectra indicating aggregation in solid state. The aggregation studies in varied THF/water fraction indicates J-aggregation for both the dyes. CCTh with thiophene linker showed broader absorption compared to CCBz, and the photovoltaic performance recorded for CCTh directly indicates better light harvesting ability corresponding to the red shifted J-aggregated states. Hence, solar cells fabricated with CCTh gave a power conversion efficiency of 3.39% and CCBz delivered an efficiency of 2.03% under full sun condition. A detailed investigation of device dynamics have been carried out employing charge extraction (CE), intensity-modulated photovoltage spectroscopy (IMVS) and open-circuit voltage decay (OCVD) measurements.
ISSN:0038-092X
1471-1257
DOI:10.1016/j.solener.2018.09.073