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Dye-sensitized solar cells (DSSCs) continue to attract as one of the most important renewable energy technologies due to their simple production, environmentally friendly, and lower-cost fabrication process compared to the most common types of solar cells. Zinc oxide (ZnO) nanostructures have motivated researchers to fabricate DSSCs as photo-anodes due to their unique properties, such as different types of structures, appropriate optical properties, proper energy bandgap, and high electron transfer characteristics. This article reports the simple preparation of ZnO tetrapod-like nanorods using the wet thermal evaporation method on porous silicon substrate PS/Si and applied as a photoanode on DSSCs. ZnO nanostructures were characterized by using grazing-angle X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) measurements. A significant difference in the performance of DSSCs has been investigated by using a standard dye di-tetrabutylammonium cis–bis(isothiocyanate)bis(2,2${}^{\prime }$-bipyridyl-4,4${}^{\prime }$-dicarboxylato) ruthenium (II) (N719) reloaded on ZnO tetrapod-like nanorods ($J_{\mathrm{\text{sc}}}=3.33$, $V_{\mathrm{\text{oc}}}=0.88$, $\mathrm{\text{FF}}=51$%, and $\eta =1.51$%) being more efficient than the ZnO spherical nanoparticles as a reference solar cell ($J_{\mathrm{\text{sc}}}=2.01$, $V_{\mathrm{\text{oc}}}=0.86$, $\mathrm{\text{FF}}=49$%, and $\eta =0.89$%).

Derived from diarylamine sensitizer diphenyl-(7-pyridin-4-yl-9H-carbazol-2-yl)-amine (N13), a series of novel D$-\pi -$A carbazole-based organic dye sensitizers with different $\pi$-linkers were designed for searching more effective sensitizers in dye-sensitized solar cells (DSSCs) design. Optimized geometries, electronic structure, and other parameters, which can evaluate the performance of DSSCs effectively and intuitively, were theoretically calculated by density functional theory (DFT) and time-dependent DFT methods at the M06/6-31G(d,p) level. The results indicated that the maximum absorption wavelength of designed dye was red-shifted and the molar absorption coefficient ($\epsilon$) became higher. This phenomenon can be explained by the modification of the $\pi$-bridge. The simulated Ultraviolet–visible spectroscopy (UV-Vis) absorption spectrum showed that the designed N,N-diphenyl-7-(5-(7-(5-(pyridin-4-yl)thiophen-2-yl)benzo[c][1,2,5]thiadiazol-4-yl)thiophen-2-yl)-9H-carbazol-2-amine (N22) dye presents the largest red-shifted absorption band and the designed (E)-N,N-diphenyl-7-(2-(5${}^{\prime }$-(pyridin-4-yl)-[2,2${}^{\prime }$-bithiophene]-5-yl)vinyl)-9H-carbazol-2-amine (N21) dye showed the largest $\epsilon$, both of them depicted a high short-circuit photocurrent density ($J_{\mathrm{\text{sc}}})$. Meanwhile, the charge separation hampered by long $\pi$-linkers was also observed. These results are helpful for designing new sensitizers and providing effective guiding to experimental synthesis.

Porphyrin macrocycles play an important role in designing of fluorophores with superior light harvesting properties similar to that of antennas in biological systems. In this paper, new Zn(II)porphyrin dyes were investigated to improve the performance of the YD2-o-C8 using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations. Effects of various substituted and anchoring groups on basic porphine and Zn(II)porphyrin derivatives were systematically studied at the B3LYP/LanL2DZ level. The absorption spectra of Zn(II)porphyrin derivatives bearing one, two and four anchoring groups in the meso-positions were also studied. The calculations showed that a molecule [5, 10, 15, 20-(4-carboxyphenylethynyl)porphyrinato]Zn(II) have large absorption cross-section than available in the existing porphyrin dyes. The results of these calculations would open up enormous possibilities to develop porphyrin dyes characterized by high absorption cross-section for various light harvesting applications.

MOF-based composite material is adopted to modify photoanode, and the obtained large BET area is found meaningful to the dye loading amount, which brings about a high short circuit current and incident photon to current conversion efficiency. Meanwhile, three-dimensional graphene networks (3DGNs) are employed to provide a fast transport channel for photo-induced electrons. The morphology is analyzed by SEM, TEM, XRD and Raman spectrum, and the photovoltaic performances are recorded to reveal the specific functions of MOF and 3DGNs. The synergy between MOF, 3DGNs and TiO₂ is achieved by adjusting their mass fraction. Moreover, the average size of MOF exerts a significant influence on the resulting properties resulting from the scattering ability to incident light. After corresponding optimizing, the short circuit current, open circuit voltaic, fill factor and energy conversion efficiency reach 20.5mAcm${}^{-2}$, 680mV, 0.619% and 8.63%.

In this work, the impact of extending $\pi$-bridge and the adsorption of dyes on the nanocrystalline surface of TiO₂ on photovoltaic parameters in dye-sensitized solar cells (DSSCs) has been explored. The dyes comprise phenothiazine (donor), along with benzene, furan, thiophene and selenophene ($\pi$-spacers), and cyanoacrylic acid anchoring group (acceptor). The dye geometries, charge transference, and electronic characteristics were investigated using density functional theory (DFT). The impact of extended $\pi$-bridge in conjugated systems was explored in dyes along with dyes adsorbed on TiO₂ nanocrystalline surface (dye@TiO${}_2)$. For the architecture D–$\pi$–A in this work, the dyes are effectively adsorbed on the TiO₂ nanocrystalline surface. The energy gap between HOMO and LUMO (HLG), ionization potential (IP), reorganization energies ($\lambda )$, electron affinity (EA), photovoltaic parameters, adsorption energy (AE), and total density of state (TDOS) are simulated theoretically. Additionally, our investigation illustrates that the studied organic photosensitizer dyes may have improved photovoltaic characteristics and are suitable applicants for efficient charge transportation in organic electronic materials.

A new generation of metal-free organic dyes with a range of donor (D1) and acceptors (A1-A3) were designed and examined for dye-sensitized solar cells (DSSCs) based on (3a) dye as a literature. Triphenylamine (TPA), thiophene ($\pi )$ and 2-cyanoacrylic acid groups each perform the roles of an acceptor (A), donor (D) and spacer in order to produce a D-$\pi$-A system. To investigate the intramolecular charge transfer (ICT), electronic distribution, ultra-violet visible (UV–Vis) absorption wavelengths, molecular electrostatic potential (MEP) and photovoltaic (PV) parameters of the D1 and A1–A3 molecules, density functional theory (DFT) and time-dependent DFT (TD-DFT) were used. The classification of the tunable donor D1 and A1–A3 determines the PV performance of the dye molecules. Results show that the A2 dye replacement group increases the performance of PV cells via red-shifting absorption spectra. Also, when compared to 3a, A2 dye have lower energy gap ($E_g)$ and superior UV–Vis spectra that cover the full visible range. These results demonstrate the viability of molecular tailoring as an approach to improve D-$\pi$-A sensitizer proposal for efficient DSSCs fabrication.

In this paper, newly metal-free four donor-$\pi$-acceptor (D-$\pi$-A) molecules (C1D1–C1D4) were designed and used for dye-sensitized solar cells (DSSCs) application, based on literature C1-1. Tetrahydroquinoline, thiophene, and 2-cyanoacrylic acid act as the electron-D, spacer, and electron-A/anchoring groups for all dyes, respectively, while the donor part was tuned and the effect was examined. The density functional theory (DFT) and time-dependent DFT (TD-DFT) have been used on the electronic transitions, geometric structures, absorption properties, electron injection ($\mathrm{\Delta }{G}_{\mathrm{\text{inject}}}$), dye regeneration ($\mathrm{\Delta }{G}_{\mathrm{\text{reg}}}$), light harvesting efficiency (LHE), ground and excited states of dipole moments (${\mu }_{\mathrm{\text{normal}}}$), open-circuit photovoltage ($e{V}_{\mathrm{\text{OC}}}$), molecular electrostatic potential (MEP) and Mulliken population analysis (MPA) of the dyes. The TD-DFT method using different functionals with exchange-correlational (XC) and long-range correlated (LC) was calculated to obtain literature data. The computational outcomes have displayed that the Coulomb-attenuating method (CAM-B3LYP) in conjunction with a 6-31G(d,p) basis set was proficient in calculating the UV-Vis spectra of the molecules. The frontier molecular orbitals’ (FMOs) contribution of the HOMOs and LUMOs of C1D1-C1D4 molecules can be confirming positive consequences on the regeneration and electron injection processes. In particular, C1D4 (N(CH3)₂) molecule shows a smaller energy gap ($E_g$), longer wavelength, high ${\mu }_{\mathrm{\text{normal}}}$ and $e{V}_{\mathrm{\text{OC}}}$. To conclude, these outcomes display that the calculated C1D1–C1D4 molecules are capable applicants to deliver better performance of the DSSCs.