Photo-sensitization of ZnS nanoparticles with renowned ruthenium dyes N3, N719 and Z907 for application in solid state dye sensitized solar cells: A comparative study

Visible-Light-Driven Hydrogen Release from Dye-Sensitized Hydrogen Boride Nanosheets

Hydrogen boride (HB) nanosheets are expected to be safe and lightweight hydrogen carriers because of their high gravimetric hydrogen density (8.5 wt %) and photon-driven hydrogen release under mild conditions. However, previously reported HB nanosheets respond only to ultraviolet (UV) light to release hydrogen. In this study, we develop dye-modified HB nanosheets that can release hydrogen under visible light irradiation (>470 nm) without heat input. Hydrogen generation is initiated by electron injection from excited dye molecules into the conduction band of the HB nanosheets. The conduction band of the HB nanosheets is formed by the antibonding states of the B 2py and H 1s atomic orbitals, and the electrons injected from the dye molecules react with the protons of the HB nanosheets to release gaseous hydrogen molecules. Although the hydrogen production is terminated after long-term light irradiation owing to dye oxidation and/or loss of protons in HB nanosheets, the total amount of the released hydrogen molecules corresponds to approximately 25% of the protons in HB nanosheets even under the extra mild conditions. The addition of a sacrificial agent like iodine ions and a proton source like formic acid sustained the H2 generation from the dye-modified HB nanosheets under visible light irradiation for long term.

Molecular modeling of mordant black dye for future applications as visible light harvesting materials with anchors: design and excited state dynamics

CONTEXT

In this study, new visible light harvesting dyes (MBR1-MBR5) have been designed as efficient materials with silyl based anchoring abilities on semiconducting units for future dye-solar cells applications. Their unique molecular structures of novel D-π-A_{Semiconductor} type were evaluated thoroughly by density functional theory (DFT) calculations. To enhance the optical performance in visible region, a novel dye structure (MBR) was derived from the chemical structure of mordant black (MB) dye with electron acceptor semiconducting units (MBR1-MBR5).

METHODS

The Coulomb-attenuating Becke, 3-parameter, Lee-Yang-Parr (CAM-B3LYP) functional, which had a hybrid and long-range correlation with 6-31G + (d,p), generated a [Formula: see text] (683 nm) that was very comparable to its experimental value (672 nm). The energies of highest occupied molecular orbitals (HOMO), lowest unoccupied molecular orbitals (LUMO), and their HOMO-LUMO energy gaps (HLG) were calculated. Their ionization potentials (IP) varied from 5.616 to 8.320 eV, demonstrating their good electron donating trend. The [Formula: see text] values of dyes displayed a significant red shift from MBR (682 nm) value with range 565-807 nm except MBR1 which was slightly blue shifted. The dye MBR4, which had the smallest HLG (0.23 eV) had the greatest second order nonlinear optical (NLO) response of 144,234 Debye-Angstrom^-1. The DFT calculated results provided insight into the creation of new silyl anchoring groups for future DSSCs material designs with increased stability and effectiveness. The goal of the current study is to forecast the development of novel NLO materials with a D-π-A_{Semiconductor} design that use semiconductors as anchoring groups to adhere to a surface.

Selected organic dyes (carminic acid, pyrocatechol violet and dithizone) sensitized metal (silver, neodymium) doped TiO2/ZnO nanostructured materials: A photoanode for hybrid bulk heterojunction solar cells

A photoactive nanohybrid material consisting of pyrocatechol violet, carminic acid and dithizone dyes functionalized silver and neodymium-doped TiO₂/ZnO nanostructured materials is reported here, as photoactive blend, for solid-state dye sensitized solar cell. First of all we synthesized metals (silver, neodymium) doped (TiO₂) Titanium oxide nanoparticles and their nanocomposites (TiO₂/ZnO, M-TiO₂/ZnO) using the sol-gel and reflux technique, respectively. The synthesized samples were then characterized by UV-Visible spectroscopy, X-Ray diffraction Analysis (XRD), Scanning electron microscopy (SEM), Energy dispersive X-Ray Analysis (EDX), and Fourier Transform infrared spectroscopy (FTIR). Optical studies were done through UV-Visible spectroscopy and the absorption spectra were used to calculate band gaps. The value of the energy gap for TiO₂ nanoparticles is 3.10 eV which was gradually tuned to 2.47 eV after incorporating metals (Ag and Nd) and forming respective nanocomposites. X-Ray diffraction Analysis (XRD) patterns revealed the purity and crystallinity in samples. Scanning electron microscopy (SEM) confirmed the irregular morphology (nanorods and spherical shaped) of ZnO and TiO₂ nanostructures respectively. The elemental composition of nanomaterials was successfully investigated using energy dispersive X-ray analysis (EDX). In the absence of any impurities, Fourier Transform infrared spectroscopy (FTIR) was used to identify the functional groups in synthesized material. For device fabrication, a solid-state electrolyte, P3HT, a hole conducting polymer was used. Characterization of fabricated solar cells was done using I-V measurements. Under simulated solar irradiation, the DSSC based on pyrocatechol violet sensitized neodymium doped TiO₂/ZnO nanohybrid materials exhibited the best PCE (power conversion efficiency) of 2.38 % and significantly improved Jsc (short circuit current density) of 15.68 mA/cm² as compared to carminic acid and dithizone in photovoltaic measurements. The improved power conversion efficiency of this device is ascribed to the particle size, increased dye adsorption, increased surface area and thus improved short circuit current density (Jsc).

Green synthesis of magnetically recyclable Mn0.6Zn0.4Fe2O4@Zn1-xMnxS composites from spent batteries for visible light photocatalytic degradation of phenol

Magnetic binary heterojunctions are a kind of promising photocatalysts due to their high catalytic activity and easy magnetic separation; however, their synthesis may involve high costs or secondary environmental impacts. In this work, the magnetically recyclable Mn_0.6Zn_0.4Fe₂O₄@Zn_1-xMn_xS (MZFO@Zn_1-xMn_xS, x = 0.00-0.07) photocatalysts are synthesized from spent batteries via a green biocheaching and egg white-assisted hydrothermal method. The as-synthesized photocatalysts have been comprehensively characterized in phase, morphology, texture, optics, photoelectrochemistry and photocatalytic activity. Characterization results indicate that the desired core-shell structure MZFO@Zn_1-xMn_xS composites are successfully synthesized, theirs absorption intensity in the visible light region is greatly enhanced compared to Zn_1-xMn_xS. In addition, doped Mn²⁺ in ZnS host lattice and the staggered bandgap alignment of MZFO and Zn_1-xMn_xS greatly enhances electron transfer and charge separation in the binary heterojunction system. The optimized MZFO@Zn_0.95Mn_0.05S shows the highest photodegradation performance toward phenol under the visible light irradiation, with a complete degradation of 25 mg L^-1 of phenol within 120 min, and its reactive kinetic constants is about 5.2 and 13.3 times higher than that of pure Zn_0.95Mn_0.05S and MZFO, respectively. Furthermore, the mechanism and pathways for the degradation of phenol are proposed. In addition, MZFO@Zn_0.95Mn_0.05S also exhibits a good reusability and high magnetic separation properties after 5 successive cycles. This new material has the advantages of low costs, simple reuse and great potential in application.

Organic dyes based on selenophene for efficient dye-sensitized solar cell

The investigation of dye-sensitized solar cells (DSSCs) based on different donor groups linked with cyanoacrylic acid electron acceptor by Selenophene as π-bridged (D-π-A) was performed based on density functional theory (DFT) time-dependent DFT (TDDFT). Different functional were tested W97XD, PBEPBE, CAM-B3LYP, and B3PW91, and compared with experimental results of the reference D1. The theoretical results with CAM-B3LYP functional at 6-311G (d,p) basis sets were capable of predicting the absorption maximum that has been reported experimentally. Calculations were made to establish the conformational orientation of the cyanoacrylic acid group and evaluate the effect of changing donor units' on the electronic properties of the ground state. Structural and electronic properties, along with the photovoltaic properties, were investigated. The LUMO and HOMO energy levels of these dyes can positively affect the process of electron injection and dye regeneration. Light-harvesting efficiency (LHE), injection driving force (ΔG^inject), and total reorganization energy (total) were also discussed. To further support the previous proprieties, electronic excited state energies were obtained by TDDFT// CAM-B3LYP/6-311G(d,p) calculations. The calculated results of these dyes reveal that D8 dye possessing triphenylamine donor unit has the best electronic, optical properties, and photovoltaic parameters.

A revolution of photovoltaics: persistent electricity generation beyond solar irradiation

The integration utilization of solar energy and waste energies by photovoltaics is regarded as a promising solution to resolve energy crisis and environmental pollution problems.

Structure and Photoelectrical Properties of Natural Photoactive Dyes for Solar Cells

A series of natural photoactive dyes, named as D1–D6 were successfully extracted from six kinds of plant leaves for solar cells. The photoelectrical properties of dyes were measured via UV-Vis absorption spectra, cyclic voltammetry as well as photovoltaic measurement. To theoretically reveal the experimental phenomena, the chlorophyll was selected as the reference dye, where the ground and excited state properties of chlorophyll were calculated via density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The experimental results show that the absorption peaks of those dyes are mainly distributed in the visible light regions of 400–420 nm and 650–700 nm, which are consistent with the absorption spectrum of chlorophyll. The photoelectrical conversion efficiencies of the solar cells sensitized by the six kinds of natural dyes are in the order of D1 > D4 > D2 > D5 > D6 > D3. The dye D1 performance exhibits the highest photoelectrical conversion efficiency of 1.08% among the investigated six natural dyes, with an open circuit voltage of 0.58 V, a short-circuit current density of 2.64 mA cm−2 and a fill factor of 0.70.

Long persistence phosphor assisted all-weather solar cells. Electricity generation beyond sunny days

We present here a rational design and fabrication for all-weather dye-sensitized solar cells tailored with long-persistence phosphor materials, yielding a maximized photoelectric conversion efficiency of 8.86% under simulated sunlight and up to 26% in the dark.

Ru-dye grafted CdS and reduced graphene oxide Ru/CdS/rGO composite: An efficient and photo tuneable electrode material for solid state dye sensitized polymer solar cells

This article provides a facile one step synthesis of CdS (cadmium sulphide) and CdS/rGO (reduced graphene oxide CdS nanocomposites) using DMF (N, N-Dimethyl formamide) both as a solvent and a reducing agent for the reduction of grapheme oxide. XRD (X-ray diffraction), FESEM (Field emission scanning electron microscopy), EDX (Elemental dispersive X-ray analysis), TEM (Transmission electron microscopy), UV-Vis (UV-visible) and Raman spectroscopy have been employed for the characterization of prepared samples. The prepared nano-composite was photosensitized with three well known Ru (Ruthenium) dyes i.e. N3 [cis-Bis(isothiocyanato) bis(2,2'-bipyridyl-4,4'-dicarboxylato ruthenium(II))], N719 [Di-tetrabutylammoniumcis-bis(isothiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylato) ruthenium (II)] and Z907 [cis-Bis(isothiocyanato)(2,2'-bipyridyl-4,4'-dicarboxylato)(4,4'-di-nonyl-2'-bipyridyl)ruthenium(II)]. The effect of concentration and number of anchoring groups on the grafting was extensively studied in order to explore structure-activity relationship. Photosensitization of CdS/rGO nanocomposite was evidenced by UV-Visible, PL (Photoluminiscence), FT-IR (Fourier transform infra-red) spectroscopy and I-V (current-voltage measurements). The prepared samples were found as effective electrode materials for application in SSDSSCs (solid state dye sensitized solar cells) with a maximum output efficiency of 1.01% which is two times higher than the reference device under the same experimental conditions. The components of the synthesized nanohybrid material were found to be capable of providing a uni-directional and cascade path for the flow of electrons and holes in the desired directions.