03101nas a2200229   4500008004100000022001400041245017500055210006900230260000800299300001400307490000700321520219200328653002302520653002102543653002502564653003102589653002902620100002702649700003902676700002702715856012902742       2020                        eng d  a1944-824400aAlkyl-group-wrapped unsymmetrical squaraine dyes for dye-sensitized solar cells: branched alkyl chains modulate the aggregation of dyes and charge recombination processes0 aAlkylgroupwrapped unsymmetrical squaraine dyes for dyesensitized  cJAN  a2555-25650 v123 a<p>Electron transfer processes at the interfaces dictate the factors that improve the photovoltaic parameters, such as open-circuit voltage (V-oc) and short-circuit current (J(sc)), of a dye-sensitized solar cell device, besides selection of a set of suitable anode, dye, electrolyte, and cathode materials. An inefficient charge injection process at the dye-TiO2 interface and charge recombination at the TiO2-dye/electrolyte interface have detrimental effects on improving both J(sc) and V-oc. Hence, tailoring the factors that govern the improvement of J(sc) and V-oc will be an ideal approach to get the desired sensitizers with good device efficiencies. Squaraines are far-red-active zwitterionic dyes and have a high molar extinction coefficient along with unique aggregation properties due to the large dipole moment associated with them. Here, we report a series of unsymmetrical squaraine dyes, SQS1 to SQS6, with systematic variation of alkyl groups at the sp(3)-C and N-atoms of the indoline unit that is away from the anchoring group to control the dye-dye interactions on the TiO2 surface. The branched alkyl groups help in modulating the self-assembly of sensitizers on the TiO2 surface, besides passivating the surface that helps avoid the charge recombination processes. Light harvesting efficiency and cyclic voltammetry studies of dye-sensitized TiO2 electrodes indicate that the aggregation and charge hopping process between the dye molecules can be modulated, respectively, by systematically increasing the number of carbon atoms in the alkyl groups. Such a variation in the branched alkyl group helps enhance V-oc from 672 (SQS1) to 718 mV (SQS6) and J(sc) from 7.95 (SQS1) to 12.22 mA/cm(2) (SQS6), with the device efficiency ranging from 3.82% to 6.23% without any coadsorbent. Dye SQS4 achieves the highest efficiency of 7.1% (V-oc = 715 mV, J(sc) = 13.05 mA/cm(2)) with coadsorbent chenodeoxycholic acid (CDCA) using an iodine (I-/I-3(-)) electrolyte compared to its analogues. An analysis of the incident photon-to-current efficiency profiles indicates that the major contribution to photocurrent generation is from the aggregated squaraine dyes on TiO2.</p>
10aaggregation of dye10acharge injection10acharge recombination10aDye-sensitized solar cells10aunsymmetrical squaraines1 aSingh, Ambarish, Kumar1 aKavungathodi, Munavvar, Fairoos Me1 aNithyanandhan, Jayaraj  uhttp://library.ncl.res.in/content/alkyl-group-wrapped-unsymmetrical-squaraine-dyes-dye-sensitized-solar-cells-branched-alkyl02527nas a2200253   4500008004100000022001400041245011700055210006900172260000800241300001400249490000800263520162300271653002301894653004201917653003001959653001801989100002402007700002702031700001702058700001702075700003002092700002702122856012402149       2024                        eng d  a0031-865500aFar-red active unsymmetrical squaraine dyes containing N-arylated indoline donors for dye sensitized solar cells0 aFarred active unsymmetrical squaraine dyes containing Narylated   cJUL  a1116-11260 v1003 a<p>
	Squaraine dyes possess sharp far-red active transition with high extinction coefficient and form aggregates on TiO2 surface. Aggregation of dyes on TiO2 has been considered as a detrimental factor for DSSC device performance, which can be controlled by appending alkyl groups to the dye structures. Hence by integrating alkylated (alkyl groups with both in-plane and out-of-plane) aryl group with indoline moiety to make it compatible with other electrolytes and for controlling the dye-aggregation, a series of squaraine acceptor-based dyes SQA4-6 have been designed and synthesized. SQA4-6 dyes showed absorption between 642 and 653 nm (lambda max), photophysical and electrochemical studies indicated that the HOMO energy levels of this sets of dyes are well aligned with the potentials of I-/I3-\$\$ {\textbackslashmathrm{I}}_3&lt;\^&gt;{-} \$\$ and [Co(bpy)3]2+/3+ redox shuttles for better dye regeneration process. DSSC device efficiency of 3% has been achieved for SQA5 dye with iodolyte (I-/I3-\$\$ {\textbackslashmathrm{I}}_3&lt;\^&gt;{-} \$\$) electrolyte in the presence of 0.3 mM of chenodeoxycholic acid (CDCA). The IPCE profile of DSSC device fabricated with SQA4-6 dyes indicated the contribution of aggregated structures for the photocurrent generation. Dye-sensitized solar cell (DSSC) device efficiency of 3% (Jsc 5.72 mA cm-2, Voc 662 mV and ff 79%) has been achieved for an unsymmetrical squaraine dye, SQA5 with iodolyte electrolyte and the incident photon to current efficiency (IPCE) profile indicates the contribution of aggregated structures for the photocurrent generation.*image</p>
10aaggregation of dye10aarylation on N-atom of indoline donor10adye-sensitized solar cell10asquaraine dye1 aJadhav, Avinash, P.1 aSingh, Ambarish, Kumar1 aPandya, Rinu1 aVanka, Kumar1 aKrishnamoorthy, Kothandam1 aJayaraj, Nithyanandhan  uhttp://library.ncl.res.in/content/far-red-active-unsymmetrical-squaraine-dyes-containing-n-arylated-indoline-donors-dye