@article {48746, title = {Visible-light-active unsymmetrical squaraine dyes with 1 V of open-circuit voltage for dye-sensitized solar cells}, journal = {ChemPhotoChem}, volume = {7}, year = {2023}, month = {MAY}, type = {Article}, abstract = {

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.

}, keywords = {Cu electrolytes, dihedral angle, Dye-sensitized solar cells, open circuit voltage, squaraine dyes}, issn = {2367-0932}, doi = {10.1002/cptc.202200328}, author = {Singh, Amrita and Kumar Singh, Ambarish and Dixit, Ruchi and Vanka, Kumar and Krishnamoorthy, Kothandam and Nithyanandhan, Jayaraj} } @article {49283, title = {Triazatruxene amine donor-based visible-light-responsive unsymmetrical squaraine dyes for dye-sensitized solar cells}, journal = {ACS Applied Energy Materials}, volume = {7}, year = {2024}, month = {SEP}, pages = {7982-7991}, type = {Article}, abstract = {

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.

}, keywords = {aggregationof dyes, Dye-sensitized solar cells, metal-free organic dyes, self-assembly of dye, squaraine dyes, triazatruxene}, issn = {2574-0962}, doi = {10.1021/acsaem.4c01591}, author = {Ingole, Kiran Balaso and Deshmukh, Shivdeep Suresh and Verma, Tushar Singh and Krishnamurty, Sailaja and Krishnamoorthy, Kothandam and Nithyanandhan, Jayaraj} } @article {49031, title = {Visible, far-red, and near-infrared active unsymmetrical squaraine dyes based on extended conjugation within the polymethine framework for dye-sensitized solar cells}, journal = {ACS Applied Energy Materials}, volume = {7}, year = {2024}, month = {FEB }, pages = {1461-1475}, type = {Article}, abstract = {

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.

}, keywords = {aggregation of dyes, DSSC device efficiency, light-harvesting efficiency, pi-extension, polymethine framework, squaraine dyes}, issn = {2574-0962}, doi = {10.1021/acsaem.3c02610}, author = {Singh, Amrita and Singh, Ambarish Kumar and Dixit, Ruchi and Vanka, Kumar and Krishnamoorthy, Kothandam and Nithyanandhan, Jayaraj} }