02581nas a2200265 4500008004100000022001400041245010200055210006900157260000800226300001600234490000700250520165100257653003101908653002401939653003001963653001901993653003002012653001902042100001802061700002402079700003902103700001902142700002702161856012702188 2018 eng d a1944-824400aFused fluorenylindolenine-donor-based unsymmetrical squaraine dyes for dye-sensitized solar cells0 aFused fluorenylindoleninedonorbased unsymmetrical squaraine dyes cAUG a26335-263470 v103 a

A series of four unsymmetrical squaraine dyes, XSQ1-4, were synthesized using a fused fluorenylindolenine-based donor unit for dye-sensitized solar cells (DSSCs). The fused structure of fluorenylindolenine helped in moving the absorption toward the near-infrared (NIR) region, and the two sp(3)-C centers available on this donor were utilized to incorporate out-of-plane alkyl chains in opposite directions to control the dye-dye interactions on the TiO2 surface. High extinction coefficient (epsilon >= 10(5) M-1 cm(-1)) for absorbing NIR photons and suitable highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels with respect to the conduction band of TiO2 and electrolyte for charge injection and dye regeneration processes, respectively, make these dyes potential sensitizers for DSSCs. Introduction of branched alkyl groups in the pi-framework helped in controlling dye aggregation to reduce exciton quenching and assisted in TiO2 surface passivation to avoid the charge recombination process. Furthermore, having a naphthyl group on the indole part of the anchoring group containing segment helped to red-shift the absorption spectrum of dyes 15 nm toward the NIR region (XSQ3-4). Among all of the dyes under investigation, XSQ2 gave the best photovoltaic performance, having a short-circuit current density (J(SC)) of 13.99 mA cm(-2), open -circuit voltage (V-OC) of 0.66 V, and a fill factor (ff) of 0.71, with a device performance (eta) of 6.57%. Electrochemical impedance spectroscopy revealed higher electron lifetime on TiO2 for XSQ2, which helps to avoid the charge recombination process.

10aDye-sensitized solar cells10afluorenylindolenine10aH- and J-type aggregation10aNIR absorption10aout-of-plane alkyl groups10asquaraine dyes1 aBisht, Rajesh1 aSudhakar, Vediappan1 aKavungathodi, Munavvar, Fairoos Me1 aKarjule, Neeta1 aNithyanandhan, Jayaraj uhttps://library.ncl.res.in/content/fused-fluorenylindolenine-donor-based-unsymmetrical-squaraine-dyes-dye-sensitized-solar03020nas a2200229 4500008004100000022001400041245019500055210006900250260000800319300001400327490000600341520212500347653002402472653002102496653002902517653001602546653001902562100002702581700002802608700002702636856012702663 2021 eng d a2574-096200aD-A-D based complementary unsymmetrical squaraine dyes for co-sensitized solar cells: enhanced photocurrent generation and suppressed charge recombination processes by controlled aggregation0 aDAD based complementary unsymmetrical squaraine dyes for cosensi cAPR a3182-31930 v43 a

A series of donor-acceptor-donor (D-A-D) based unsymmetrical squaraine dyes have been synthesized with indoline and aniline as donor units. The sp(3)-C, N atoms of the indoline and N atom of the aniline donors are appended with alkyl groups systematically to control the self-assembly of dyes on TiO2 and to passivate the photoanode that helps in improving the open circuit voltage (V-oc) of the dye-sensitized solar cell (DSSC) device. The resulting dyes, AK1-4, possess strong absorptions between 529 and 541 nm with extinction coefficients of 1.44-1.84 X 10(5) M-1 cm(-1). Photophysical and electrochemical studies revealed that the lowest unoccupied molecular orbital and highest occupied molecular orbital of the dyes are aligned with the conduction band of TiO2 and the redox function of the electrolyte for the efficient charge injection and dye regeneration processes, respectively. A DSSC device performance for AK4 of 7.93% (V-oc of 815.88 mV and short circuit current density (J(sc)) of 12.4 mA/cm(2)) is obtained, with an incident photon to current conversion efficiency (IPCE) response of 92% at 473 nm and 86% at 566 nm without sensitizing with coadsorbent. IPCE studies revealed the equal contribution for the photocurrent generation from the H-aggregated structures. Further, such a high V-oc and DSSC efficiency have been observed first time for this class of zwitterionic dyes with the I-/I-3(-) electrolyte without sensitizing with coadsorbent. The importance of introducing the alkyl groups at the indoline as well as aniline donor units for the synergistic boosting of both V-oc, and J(sc) is compared with the model dye AK1. Complementary light absorbing dyes SQ1 and SQS4 possess absorption at 643 nm with extinction coefficients of 1.4 and 3.0 x 10(5) M-1 cm(-1), respectively. A cosensitized device performance of 9.36% is obtained for the AK4:SQS4 (1:1) combination in the I-/I-3(-) electrolyte. The IPCE profile indicates a good response over 450-700 nm with 94% at 621 nm. The importance of aggregated structures from both the dyes AK4 and SQS4 for photocurrent generation is realized.

10aaggregation of dyes10aco-sensitization10aextension of conjugation10aH-aggregate10asquaraine dyes1 aSingh, Ambarish, Kumar1 aVeetil, Athulya, Nellur1 aNithyanandhan, Jayaraj uhttps://library.ncl.res.in/content/d-d-based-complementary-unsymmetrical-squaraine-dyes-co-sensitized-solar-cells-enhanced01964nas a2200253 4500008004100000022001400041245011800055210006900173260000800242490000600250520107500256653002001331653001901351653003101370653002501401653001901426100001801445700002701463700001701490700001701507700003001524700002701554856012901581 2023 eng d a2367-093200aVisible-light-active unsymmetrical squaraine dyes with 1 V of open-circuit voltage for dye-sensitized solar cells0 aVisiblelightactive unsymmetrical squaraine dyes with 1 V of open cMAY0 v73 a

A series of alkyl-group-functionalized, aniline- and indoline-donor-based, unsymmetrical visible-light-active squaraine dyes, AM1-3, were designed and synthesized. Dye-sensitized solar cell (DSSC) devices were fabricated with both I-/I-3(-) and [Cu(tmby)(2)](+/2+) electrolytes. DSSC devices sensitized with the AM1 and AM2 dyes showed relatively high-power conversion efficiency of 7.44 % and 7.22 %, respectively with I-/I-3(-) in the absence of chenodeoxycholic acid (CDCA) than those of the AM3 dye (5.41 %). The [Cu(tmby)(2)](+/2+) electrolyte along with poly(3,4-ethylenedioxythiophene) (PEDOT) as cathode material showed excellent open-circuit potentials (V-OC) of 1030, 1025, and 1001 mV with the DSSC efficiency of 8.05 %, 7.96 %, and 5.84 %, respectively, for the AM1, AM2, and AM3 dyes in the absence of CDCA. Here, the AM1 dye exhibited the maximum DSSC efficiency of 8.05 % and V-OC of 1030 mV, which is the highest obtained efficiency and V-OC for the visible-light active zwitterionic unsymmetrical-squaraine dye with copper-based electrolyte.

10aCu electrolytes10adihedral angle10aDye-sensitized solar cells10aopen circuit voltage10asquaraine dyes1 aSingh, Amrita1 aSingh, Ambarish, Kumar1 aDixit, Ruchi1 aVanka, Kumar1 aKrishnamoorthy, Kothandam1 aNithyanandhan, Jayaraj uhttps://library.ncl.res.in/content/visible-light-active-unsymmetrical-squaraine-dyes-1-v-open-circuit-voltage-dye-sensitized02525nas a2200277 4500008004100000022001400041245012100055210006900176260000800245300001400253490000600267520153600273653002301809653003101832653002801863653002501891653001901916653001801935100002601953700003101979700002502010700002602035700003002061700002702091856012902118 2024 eng d a2574-096200aTriazatruxene amine donor-based visible-light-responsive unsymmetrical squaraine dyes for dye-sensitized solar cells0 aTriazatruxene amine donorbased visiblelightresponsive unsymmetri cSEP a7982-79910 v73 a

Optimized charge-transfer dynamics at the dye-TiO2/electrolyte interface are required for an enhanced dye-sensitized solar cell (DSSC) device performance. Such an optimized interface enhances the charge-injection, dye-regeneration, and diminished charge-recombination processes, synergistically enhancing the device efficiency. In this study, octupolar-structured sensitizers are designed to improve the interaction between the dye and the redox electrolyte for increasing the dye-regeneration process upon photoexcitation. Accordingly, a set of unsymmetrical squaraine dyes with indoline and triazatruxene amine donor-based D-A-D dyes are designed (KV1-KV3), synthesized, and sensitized with a semiconducting metal oxide (TiO2) film. The sensitizer forms a monolayer on the TiO2 surface, leading to a dye-dye interaction, which broadens the absorption spectrum. The N atom of the triazatruxene amine donor was left unsubstituted in KV1, whereas a hexyl chain was installed in KV2 and KV3 and a branched alkyl chain was installed on the core N atoms in KV3 to control the self-assembly of dyes on the TiO2 surface. Self-assembly of alkyl groups wrapped in KV1-KV3 dyes on the TiO2 surface aids surface passivation and broadens the absorption profile, improving the light-harvesting capabilities. The DSSC devices based on KV2 exhibited a high power conversion efficiency of 7.85% (V-oc = 794 mV, J(sc) = 14.76 mA/cm(2), and FF = 67%), with an onset incident photon-to-current conversion efficiency response from 680 nm.

10aaggregationof dyes10aDye-sensitized solar cells10ametal-free organic dyes10aself-assembly of dye10asquaraine dyes10atriazatruxene1 aIngole, Kiran, Balaso1 aDeshmukh, Shivdeep, Suresh1 aVerma, Tushar, Singh1 aKrishnamurty, Sailaja1 aKrishnamoorthy, Kothandam1 aNithyanandhan, Jayaraj uhttps://library.ncl.res.in/content/triazatruxene-amine-donor-based-visible-light-responsive-unsymmetrical-squaraine-dyes-dye02594nas a2200277 4500008004100000022001400041245017000055210006900225260000900294300001400303490000600317520158800323653002401911653002701935653003201962653001701994653002602011653001902037100001802056700002702074700001702101700001702118700003002135700002702165856012402192 2024 eng d a2574-096200aVisible, far-red, and near-infrared active unsymmetrical squaraine dyes based on extended conjugation within the polymethine framework for dye-sensitized solar cells0 aVisible farred and nearinfrared active unsymmetrical squaraine d cFEB  a1461-14750 v73 a

Alkyl group wrapped visible, far-red, and NIR active unsymmetrical squaraine dyes with pi-extension in the polymethine framework-based AM4-AM7 have been designed, synthesized, and utilized as sensitizers for dye-sensitized solar cells. To extend the pi-conjugation within the polymethine framework, thiophene moieties have been incorporated between the donor and acceptor moieties. Absorption spectroscopic studies revealed that pi-extension with each -C & boxH;C- unit resulted similar to 100 nm of redshift in the charge transfer transition with the lambda(maximum) of 541, 643, 747, and 833 nm for AM4, AM5, AM6, and AM7 dyes, respectively, with the molar extinction coefficient of >10(5) M(-1)cm(-1). The pi-extended conjugation-based AM6 and AM7 dyes showed improved light-harvesting efficiency (LHE), where the AM7 dye showed an LHE of 386 nm at 60%. Electrochemical studies of AM dyes revealed that the HOMO energy level of the sensitizers has been modulated systematically. Further, pi-extension within the polymethine framework showed a dramatic effect on V-OC, J(SC), and device efficiency when move from visible active AM4 to far-red active to NIR active AM7 dyes. The DSSC efficiencies of 7.35, 5.18, 0.08, and 0.053% have been achieved with the I-/I-3(-) electrolyte (Z-50) for the AM4, AM5, AM6, and AM7 dyes, respectively. Further, AM4 dye has been cosensitized with AM5, AM6, and AM7 dyes, where AM4:AM5 (1:1) composition achieved the maximum efficiency of 8.12% with I-/I-3(-) electrolyte (Z-50) compared to the other cosensitization compositions.

10aaggregation of dyes10aDSSC device efficiency10alight-harvesting efficiency10api-extension10apolymethine framework10asquaraine dyes1 aSingh, Amrita1 aSingh, Ambarish, Kumar1 aDixit, Ruchi1 aVanka, Kumar1 aKrishnamoorthy, Kothandam1 aNithyanandhan, Jayaraj uhttps://library.ncl.res.in/content/visible-far-red-and-near-infrared-active-unsymmetrical-squaraine-dyes-based-extended02640nas a2200289 4500008004100000022001400041245015900055210006900214260000800283300001100291490000800302520162200310653002401932653002101956653002401977653003102001653002502032653001902057653001802076100002602094700001602120700001702136700001702153700003002170700002702200856012302227 2025 eng d a1010-603000aDouble anchoring squaraine dye with triazatruxene amine donor for dye-sensitized solar cells: sequential cosensitization for panchromatic light-harvesting0 aDouble anchoring squaraine dye with triazatruxene amine donor fo cMAY a1162290 v4623 a

Dyes are firmly bound to a semiconducting TiO2 film using carboxylic acid anchoring groups for an efficient electron transfer from the excited state of dye to the conduction band (CB) of TiO2. Strong dye binding can be accomplished with multi-anchoring dye designs to improve photophysical characteristics, including high extinction coefficients, panchromatic absorption, post-sensitization modifications, and dark current suppression, besides enhancing the stability of the dye-TiO2 interface. Herein, a novel KV2D dye with double squaraine acceptor and double carboxylic acid anchoring groups is designed to achieve a high extinction coefficient (epsilon, 3.57 x 105M-1cm-1) and robust binding to the TiO2 film for an effective electron transfer. We systematically changed the amount of coadsorbent chenodeoxycholic acid (CDCA) to control the aggregation of dyes on the TiO2 surface that improves the power conversion efficiency (PCE, eta) for the devices based on the doubleanchoring KV2D. Out of these devices, KV2D: CDCA (1:10) based cell exhibited the best PCE of 5.26% with VOC of 754 mV, JSC of 10.41 mA/cm2, and ff of 67%. The sequential cosensitization studies were carried out with a far-red active dye to find the effect of the strong binding of the sensitizer to the TiO2 film. Interestingly, when di-anchoring, KV2D was sensitized first for 12 h and then sequentially cosensitized with far-red absorbing SQS4 for 5 h to achieve a PCE of 5.0% with VOC of 697 mV, JSC of 10.23 mA/cm2, and ff of 70% with panchromatic spectral response in IPCE upto 730 nm giving higher photocurrent generation.

10aaggregation of dyes10aBulky donor unit10aDouble acceptor dye10aDye-sensitized solar cells10aself-assembly of dye10asquaraine dyes10atriazatruxene1 aIngole, Kiran, Balaso1 aSiby, Jesna1 aPandya, Rinu1 aVanka, Kumar1 aKrishnamoorthy, Kothandam1 aNithyanandhan, Jayaraj uhttps://library.ncl.res.in/content/double-anchoring-squaraine-dye-triazatruxene-amine-donor-dye-sensitized-solar-cells02224nas a2200253 4500008004100000022001400041245018000055210006900235260000800304490000700312520127300319653002101592653003101613653002501644653001901669653001801688100002601706700001601732700001701748700001701765700003001782700002701812856013101839 2026 eng d a1861-472800aAuxiliary triazatruxene donor-based squaraine dyes for dye-sensitized solar cells: cis- and trans- configuration of dyes for modulating photophysical and electronic properties0 aAuxiliary triazatruxene donorbased squaraine dyes for dyesensiti cJAN0 v213 a

In DSSCs, dye regeneration efficiency and dye aggregation on the TiO2 surface can be modulated by using bulky aromatic donors wrapped with alkyl groups. Introduction of rigid aromatic rings around the donor unit of a dye will directly impact the driving force for electron injection and dye regeneration of a dye. In this work, we designed and synthesized KNS dyes with an auxiliary TAT donor integrated with a visible active squaraine dye. Here, octupolar-structured auxiliary TAT wrapped with alkyl groups is used as a strong donor and shelter to reduce the dye aggregation and charge recombination process. Further, to improve the light-harvesting efficiency and incident photon-to-current conversion efficiency of DSSC devices fabricated with KNS dyes, the central squaric acid unit has been modified by appending the electron-withdrawing dicyano group at the central squaric unit, and the trans-configured KNS1 dye was converted to cis-configured KNS2 dye. The power conversion efficiency of devices based on the KNS dyes was studied with and without 3 equivalents of CDCA by using the I-/I3 - electrolyte. Out of these devices, the KNS1: CDCA (1:3) based cell exhibited the best PCE of 6.25% with V OC of 793 mV, J SC of 11.08 mA cm-2, and ff of 71%.

10aBulky donor unit10aDye-sensitized solar cells10aself-assembly of dye10asquaraine dyes10atriazatruxene1 aIngole, Kiran, Balaso1 aSiby, Jesna1 aPandya, Rinu1 aVanka, Kumar1 aKrishnamoorthy, Kothandam1 aNithyanandhan, Jayaraj uhttps://library.ncl.res.in/content/auxiliary-triazatruxene-donor-based-squaraine-dyes-dye-sensitized-solar-cells-cis-and-trans02133nas a2200229 4500008004100000022001400041245012400055210006900179260000900248300001100257490000800268520131200276653002501588653002001613653003101633653002301664653001901687653002401706100001601730700002701746856013001773 2026 eng d a1010-603000aD-A-D based NIR and visible homodimeric squaraine dyes for dye-sensitized solar cells: Modulation of excitonic coupling0 aDAD based NIR and visible homodimeric squaraine dyes for dyesens cAPR  a1168740 v4733 a

Dye-TiO2 interface plays a crucial role in the overall performance of dye-sensitized solar cells. Anchoring groups help to bind the dye on TiO2 and inject the electrons to the conduction band of TiO2. In this work, a series of homodimeric NIR squaraine dyes C6NIR, C10NIR, and visible squaraine dyes C6VIS, C10VIS are designed and synthesised. These dimeric dyes are covalently connected by decyl or hexyl units between the nonanchoring side of their monomeric unit. Optical spectroscopy in solution and on TiO2 surface indicates that the excitonic coupling between the dyes can be modulated. All the dimeric dyes showed better photovoltaic performance than their corresponding monomeric dyes. The dyes showed device performance SQ1 (1.28%) < C6NIR (2.26%) < C10NIR (2.79%) and AK2 (3.59%) < C6VIS (4.34%) < C10VIS (5.28%) respectively. The dimeric dyes showed better light harvesting efficiency and better passivation of the TiO2 surface. It helps to enhance the device's overall performance by improving the photocurrent and open circuit voltage. The decyl-linked dimeric dyes showed better performance among this set of dyes and C10NIR dyes showed V-oc of 614 mV, J(sc) of 7.08 mA/cm(2), and ff of 64.2%. and C10VIS showed V-oc of 724 mV, J(sc) of 10.74 mA/cm(2), and ff of 67.9%.

10acharge recombination10aDye aggregation10aDye-sensitized solar cells10aDye-TiO2 interface10asquaraine dyes10asurface passivation1 aSiby, Jesna1 aNithyanandhan, Jayaraj uhttps://library.ncl.res.in/content/d-d-based-nir-and-visible-homodimeric-squaraine-dyes-dye-sensitized-solar-cells-modulation