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Two series of dyes have been designed and theoretically characterized through density functional theory and time-dependent density functional theory to systematically explore the structure-property relationship of dyes with D-A-π-A architecture and the performance of dye-sensitized solar cells, particularly the influence of the π-bridge, including its alkyl side chain, adding additional conjugate spacer, displacement, and separation of π-bridge. Key parameters associated with the short-circuit current density Jsc and open-circuit photovoltage Voc were characterized and analyzed in detail. All of the analysis results manifest that dye H1 should be the best candidate to fabricate dye-sensitized solar cells owing to the best optical absorption property (a broad absorption band from 300 to 900 nm for adsorbed dye) and other outstanding parameters. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations have been carried out to explore the underlying origin of merits for rigid π-spacer based on reference dyes C255 and C254 . The results demonstrate that higher short-circuit current density ( J SC ) of C255 is primarily ascribed to the lower EBE , while the biggish short-circuit current density ( V OC ) mainly originates from the larger μ normal compared to C254 . Besides, a novel index integral of overlap between hole and electron ( S ) is firstly introduced to quantitatively estimate the facility of intramolecular charge transfer (ICT) and preliminarily confirmed to be effective for the research target of this work. Furthermore, three series of dyes (C-series, A-series, AC-series) have been designed and characterized to screen promising sensitizer candidates and design strategies, while delightful results have been achieved including 6 promising candidates, design stratagem on efficiently reducing the charge recombination and combinational tactics on screening new dyes with excellent spectral properties or outstanding DSSC performance. [ABSTRACT FROM AUTHOR]

Abstract: Six indoline-based dyes 1–6 used in DSSCs with difference in π spacer were theoretically researched and verified using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) to shed light on how the additional (auxiliary) acceptor and π spacer order influence the performance of the dye. Key parameters associate with the short-circuit current density (J sc) and open-circuit photovoltage (V oc), including light-harvesting efficiency LHE, electron injection driving force ΔG inject, total reorganization energy λ total (λ h and λ e), the vertical dipole moment μ normal, the energy differences eV oc between E LUMO and E CB as well as the extent of electron recombination were characterized. The theoretical results reveal that compared with dye 1, dyes 2–6 improve the performance potentially due to their auxiliary acceptor. These enable us to determine these factors related to the J sc and V oc can be significantly influenced by the incorporated electron-withdrawing subunit into molecular backbone. [Copyright &y& Elsevier]

A novel organic dye with 2D-A structure has been designed and calculated whereby density functional theory (DFT) and time-dependent density functional theory (TD-DFT) for dye-sensitized solar cells. The double-donor branched dye which was consisted of two separated light-harvesting moieties was beneficial to photocurrent generation. First, we discussed the effects of different donor chains on photoelectric performance in the dye molecule, using the DTP-B8 which was a previously reported structure as the reference. Only to conclude that the suitable length can achieve the satisfactory efficiency. Secondly, to modify and sift potential sensitizers further, three series of dyes (BC-series, CB-series and CC-series) were designed and characterized. The increased molar extinction coefficient and the red-shifted λ max was attributed to an increasing in electron conjunction. This work presented a new route to design sensitizers that provide two channels for donating more electrons and improve the final efficiency. It is expected to provide some theoretical guidance on designing and synthetizing high efficiency photosensitive dye in the future experiments. [ABSTRACT FROM AUTHOR]

Abstract: Series sensitizers of indoline and triphenylamine as the donor group, quinoxaline and its derivatives as the additional acceptor, different heteroaromatic rings (furan, benzene and selenophene) as the π-conjugated group, 2-cyanoacrylic acid as the acceptor/anchoring which featured on the D–A–π–A architecture have been theoretically designed based on the reported dyes IQ2 and TQ2 used in dye-sensitized solar cells (DSSCs), to shed light on how the additional (auxiliary) acceptor and π spacer influence the performance of the dyes. These enable us to determine master factors influenced the efficiency of DSSCs, such as the light-harvesting efficiency, lifetime of excited state, exciton binding energy, total reorganization energy and electron injection driving force as well as the vertical dipole moment. The theoretical results revealed that compared with dye IQ2, our designed dyes IQS2 and IQS3 displayed much better light harvesting properties and longer first excited lifetime. [Copyright &y& Elsevier]