@article {43309,
	title = {Panchromatic sensitizer for dye-sensitized solar cells: un-symmetrical squaraine dyes incorporating benzodithiophene π-spacer with alkyl chains to extend conjugation, control the dye assembly on TiO2 and retard charge recombination},
	journal = {Journal of Organic Chemistry},
	volume = {82},
	year = {2017},
	month = {JAN},
	pages = {1920{\textendash}1930},
	abstract = {Metal-free near-infrared (NIR) active unsymmetrical squaraine dyes, RSQ1 and RSQ2, with benzodithiophene (BDT) π-spacer and cyanoacrylic acid acceptor were synthesized by utilizing palladium catalyzed direct (hetero)arylation reaction. Methyl and 2-ethylhexyl groups were strategically placed at the BDT unit for RSQ1 and RSQ2 respectively, to investigate the effect of alkylated π-spacer on dye aggregation on the TiO2 surface and recombination reactions at TiO2/dye/electrolyte interface. These dyes have strong absorption ( ε>10(5) M(-1)cm(-1)) in near-infra red (NIR) region and exhibit similar optical and electrochemical properties as they have same conjugated framework. RSQ2 performed better than RSQ1 owing to its higher open-circuit voltage (Voc) and fill factor (ff) in spite of having comparable short-circuit current density (Jsc). The panchromatic incident photon-to-current conversion efficiency (IPCE) response was also observed for both the dyes. RSQ2 showed power conversion efficiency (PCE) of 6.72\% with short-circuit current density (Jsc) of 18.53 mA/cm(2), open circuit voltage (Voc) of 0.538 V, and fill factor (ff) of 67.4\%, without any co-adsorbent. Attenuation of the charge recombination for RSQ2 was revealed by electrochemical impedance analysis (EIS) and open-circuit potential decay transients (OCVD), which attributes to its higher Voc and ff in comparison to RSQ1.
},
	doi = {10.1021/acs.joc.6b02670},
	author = {Bisht, Rajesh and Munavvar, Fairoos Mk and Singh, Ambarish Kumar and Nithyanandhan, Jayaraj}
}
@article {46421,
	title = {pi-Extended cis-configured unsynimetrical squaraine dyes for dye-sensitized solar cells: panchromatic response},
	journal = {ACS Applied Energy Materials},
	volume = {2},
	year = {2019},
	month = {DEC},
	pages = {8464-8472},
	type = {Article},
	abstract = {<p>{Light absorbing sensitizer is the heart of the third generation photovoltaic technologies such as dye sensitized solar cells. Despite possessing large extinction coefficients for the metal-free organic dyes, the light harvesting efficiency is limited with the narrow absorption 20 profile in either visible or NIR regions of the solar spectrum. Though monolayer formation of organic sensitizers on semiconducting metal oxide surface leads to dye-dye interaction that leads to broadening the absorption profile, the contribution of the aggregated state to the power conversion process is found out to be poor. Here, we have engineered far-red active pi-extended cis-configured unsymmetrical squaraine dyes with carboxylic acid and cycnoacetic acid as anchoring groups with controlled aggregation and panchromatic light absorption by including the steric and electronic factors. The presence of sp(3)-C (out-of-plane) and N-alkyl (in-plane) groups played an important role in modulating the assembly of the dyes on the TiO2 electrode; the cis-squaraine unit helps to extend the conjugation in the NIR region besides enhancing the visible transition and the incident photon-to-current conversion efficiency profile that showed the importance of anchoring groups for the panchromatic response. Dye PSQ10 showed solar-to electric conversion with an onset of 850 nm with the device performance of 7.0\% (V-oc = 0.581 V, J(sc) = 17.06 mA/cm(2)</p>
},
	keywords = {cis-squaraine dyes, Dye aggregation, Dye-sensitized solar cells, extended far-red absorption, panchromatic response},
	issn = {2574-0962},
	doi = {10.1021/acsaem.9b01341},
	author = {Punitharasu, Vellimalai and Kavungathodi, Munavvar Fairoos Mele and Singh, Ambarish Kumar and Nithyanandhan, Jayaraj}
}
