Design of Efficient Metal-Free Organic Dyes Having an Azacyclazine Scaffold as the Donor Fragment for Dye-Sensitized Solar Cells

Abstract

The energy conversion efficiency of dye-sensitized solar cells derived from organic dye molecules has seen immense interest recently. In this work, we report a series of organic donor molecules with enhanced energy conversion efficiency using π-spacers and cyanoacrylic acid as an anchoring group (2−6). Density functional theory (DFT) and timedependent DFT calculations of these molecules have been performed to examine their electronic structures and absorption spectra before and after binding to the semiconductor titanium dioxide surface. The computational results suggest that dyes 4 and 6 have a larger driving force (ΔG inject = −1.66 and −1.80 eV, respectively) and light-harvesting efficiency (LHE = 0.99) in the series of donor molecules studied. Thus, these dyes should possess a larger short-circuit photocurrent density (J sc ) compared to the other examined dyes. The reported ΔG inject (−1.62 eV) and LHE (0.98) for compound 1, calculated with the same level of theory, were lower than those of the designed 4 and 6 dyes. Furthermore, the DFT calculations showed that the open-circuit photovoltage (V oc ) is improved with the vertical dipole moment and number of photoinjected electrons for 4 and 6. Dyes 4 and 6 are expected to exhibit high solar-energy-to-electricity conversion.

Promising sensitizers for dye sensitized solar cells: A comparison of Ru(II) with other earth's scarce and abundant metal polypyridine complexes

“…In this article, we have calculated different properties of the tris bipyridine complex with different scarce and abundant metal ions coupled to well‐known anchoring groups used for DSSCs (Scheme ) . Four of them (the first four in Scheme ) have been used for the Ru‐bipyridine dye for NiO p‐SC by Pellegrin et al First of all, we considered structural properties such as the interaction energy of the metal ions with the dye and the change of dihedral angles upon interaction with the various metal ions and different anchors.…”

“…The overall conversion efficiency ( η ) of such DSSCs can be quantified by means of where V OC is the open‐circuit photovoltage, J SC the short‐circuit current density, FF the fill factor, and P inc the incident solar power. The short‐circuit current density is determined from the integral of the product of the LHE at a given wavelength, LHE ( λ ), the efficiency of hole injection ( Φ inject ), dye regeneration efficiency ( Φ regen ), and charge collection efficiency ( Φ coll ).…”

“…The short‐circuit current density is determined from the integral of the product of the LHE at a given wavelength, LHE ( λ ), the efficiency of hole injection ( Φ inject ), dye regeneration efficiency ( Φ regen ), and charge collection efficiency ( Φ coll ). The LHE can be expressed as: where f is the oscillator strength of the adsorbed dye molecule at the respective absorption maximum, λ max .…”

The influence of noncovalent interactions in metal‐free organic dye molecules to augment the efficiency of dye sensitized solar cells: A computational study

“…The experimentally reported maximum absorption spectra (λ max ) are compared with the λ max obtained at different DFT functionals. The reported dyes ( 1 , 3 , 5 , 7 , and 9 ) were optimized with B3LYP/6–31G* level of theory and the λ max values were calculated using different DFT functionals with larger basis set: B3LYP/6‐31 + G*, M062X/6‐31 + G*, ωB97XD/6‐31 + G*, bp86/6‐31 + G*, PBE0/6‐31 + G* MPW1K/6‐31 + G*, and CAM‐B3LYP/6‐31 + G* (Table ) . The calculated results suggest that the ωB97XD/6 − 31 + G* method is in better agreement with the experiment λ max than other functionals and hence it is used for further studies.…”

“…The experimentally reported maximum absorption spectra (Table 1). [53][54][55][56][57][58][59][60][61] The calculated results suggest that the xB97XD/6 2 31 1 G* method is in better agreement with the experiment k max than other functionals and hence it is used for further studies.…”