Photoelectrochemical Solar Cells Research Articles

Cost-effective liquid-junction solar devices with plasma-implanted Ni/TiN/CNF hierarchically structured nanofibers

Carbon-based conductive materials have been recognized as promising alternatives to noble metals as the electrode in optoelectronic devices. Herein, by utilizing energetic plasma ion implantation, Ni-doped TiN nanowire (NWs) modified graphitic carbon nanofibers (CNF) are designed and prepared as the candidates of the platinum (Pt) counter electrode for low-cost hybrid perovskite-based liquid-junction photoelectrochemical solar cells (LPSCs). Notably, the photoelectrochemical (PEC) response of p-Rb0.05FA0.95PbI3 based-LPSCs equipped with the Ni/TiN/CNF counter electrode is almost identical to that with a typical Pt counter electrode. From electrochemical investigations, i.e., electrochemical impedance spectroscopy (EIS), we observe that the CNF-based materials show a similar redox activity compared with the Pt counter electrode, indicating low charge-transfer resistance (Rct) and large capacitance (C). The LPSCs, with a configuration of p-Rb0.05FA0.95PbI3/BQ (2 mM), BQ− (2 mM)/Ni/TiN/CNF-based counter electrode, exhibit an open-circuit photovoltage of 1.00 V and a short-circuit current density of 7.02 mA/cm2 under 100 mW/cm2 irradiation. The overall optical-to-electrical energy conversion efficiency is 5.06%. The PEC solar cell shows good stability for 5 h under irradiation. The CNF-based counter electrode enables potential applications, including but not limited to PEC solar devices, dye-sensitized solar cells (DSSCs), solar fuel devices and hydrogen evolution reaction.

Determination of rutile transition metal oxide (110) surface terminations by scanning tunneling microscopy contrast reversal

The surfaces of rutile transition-metal oxides $({\mathrm{TMO}}_{2})$ are widely investigated for catalysis, photoelectrochemical solar cells, memristors, and supercapacitors, but their structures have remained controversial. Here we employ density functional theory to predict that a universal behavior of metallic ${\mathrm{TMO}}_{2}$ surfaces, i.e., the stoichiometric ${\mathrm{TMO}}_{2}$ surfaces, exhibit a contrast reversal in simulated scanning tunneling microscopy (STM) images at different scanning biases. The predictions are verified by experimental STM imaging of ${\mathrm{RuO}}_{2}(110)$ surfaces and this feature is shown to enable accurate determinations of the ${\mathrm{TMO}}_{2}(110)$ surface structures under various conditions. This work provides different insights into the electronic properties of ${\mathrm{TMO}}_{2}(110)$ surfaces and offers an effective method to directly map the surface structure and point defects using bias-dependent STM.

Chalcogen-vacancy group VI transition metal dichalcogenide nanosheets for electrochemical and photoelectrochemical hydrogen evolution

Chalcogen vacancies of MoS2, MoSe2, WS2, and WSe2 nanosheets enhanced the catalytic hydrogen evolution reaction in solar photoelectrochemical cells.

Ta2O5 NTs-TiO2 nanodots heterostructure photocatalyst material for enhanced photodegradation and photoelectrochemical performance under simulated solar light

Ta2O5-TiO2 heterojunction photocatalysts with a structure of TiO2 nanodots deposited on Ta2O5 nanotube (NTs) were prepared by anodization and in situ growth methods following annealing treatment. The heterojunction photocatalytic material exhibited enhanced photodegradation behavior of methylene blue (MB) and photoelectrochemical water splitting performance under simulated solar light. The degradation rate of MB and photocurrent density of heterojunction is 3.99 and 8.33 times higher than that of pure Ta2O5 NTs respectively. The synergetic effect of the phase heterojunction and highly ordered structure increased the specific surface area and improved the separation and transmission efficiency of photogenerated electrons and holes, thereby enhancing the photocatalytic activities. Hence, Ta2O5 TNs-TiO2 nanodots heterojunction has promising application in the fields of photodegradation, photoelectrochemical water splitting, solar cells, and other photocatalytic devices.

Tunable morphology and band gap alteration of CuO-ZnO nanostructures based photocathode for solar photoelectrochemical cells

A homogeneous CuO-ZnO nanostructure with tunable morphology and optical band structure is successfully synthesized via a hydrothermal method under the different dopant mole ratios of Cu. The robust correlation between the crystallite size, surface morphology, optical band gap alteration of the synthesized CuO-ZnO and its performance in photoelectrochemical (PEC) activity are investigated and compared to the reference ZnO based photocathode. In this report, it is found that the morphology of hexagonal ZnO nanorod is changed to nanosheet and vertically align CuO-ZnO based nanograss after the Cu incorporation. This result is mainly due to the composition phase change after the excessive incorporation of Cu metal into ZnO lattice. Furthermore, the optical band gap of the sample also presented a bathochromic shifted after the Cu insertion. The measurements on PEC activity of CuO-ZnO nanostructure was performed under the irradiation of a 100 mWcm−2 Xenon light in 0.5M Na2SO4 electrolyte. Among the sample, 0 Zn:1 Cu exhibited a highest photocurrent density which is 5 fold as compared to its reference ZnO samples. This finding could be due to the highest surface active area and lowest optical energy band gap in the 0 Zn:1 Cu nanograss that eventually contributes to a high free electron density that facilitates the charge transport in the photoelectrochemical cells. This novel approach could provide an alternative to the future solar hydrogenation application.

Leaf-like MXene nanosheets intercalated TiO2 nanorod array photoelectrode with enhanced photoelectrochemical performance

In this study, a new photoelectrochemical material is fabricated by loading two-dimensional leaf-like Ti3C2 MXene nanosheets into the TiO2 nanorod array to form Ti3C2 nanosheets/TiO2 nanorod (Ti3C2/TiO2 NR) composite photoanode materials. The unique two-dimensional/one-dimensional (2D/1D) composite photocatalytic materials enhance the photoelectrochemical water splitting performance under simulated solar light (100 mW cm−2) and yield a high photocurrent density of 1.41 mA cm−2 at 1.23 V vs. reversible hydrogen electrode (Vvs.RHE) and photoconversion efficiency of 0.46% at 0.78 Vvs.RHE, which are almost 3.13 and 5.82 times higher, respectively, than those of the pure rutile TiO2 NRs. The enhanced photoelectrochemical performances are attributed to the photogenerated electrons produced by TiO2 NR which could be quickly transported by Ti3C2 nanosheets due to their good electrical conductivity and increased specific surface area, which improve the separation efficiency of electrons and holes. These Ti3C2/TiO2 NR, as new photocatalytic materials, have promising potential applications in the fields of photoelectrochemical water splitting, solar cells, and other photocatalytic devices.

Core-shell cadmium sulphide @ silver sulphide nanowires surface architecture: Design towards photoelectrochemical solar cells

Design and development of cadmium sulphide core with silver sulphide shell assembly in nanowire (NWs) surface architecture has been explored through room temperature, simple chemical route towards photoelectrochemical solar cell application. Incorporation of low band gap Ag2S nanoparticles over the outer surface of the chemical bath deposited CdS NWs has been achieved by simple cation exchange route based on negative free energy of formation. Shell optimization has been performed by investigating structure, surface morphologies and optical analyses and correlated with the photovoltaic parameters. Interestingly, core–shell CdS NWs/ Ag2S exhibits 1.5 better performance in terms of linear voltammetry, photocurrent transient response and the photo stability than bare CdS. Furthermore, three-fold enhancement in photoelectrochemical conversion efficiency have been observed for optimized FTO/ CdS NWs/Ag2S compared to bare FTO/CdS NWs due to the augmented light harvesting and condensed charge recombination. External quantum efficiency exhibits 24% for the optimized CdS NWs/ Ag2S core shell structure. Mott-Schottky and electrochemical impedance spectroscopy measurements have been used for better understanding the impact of gradual growth of Ag2S over CdS NWs which directly influences the overall photocurrent density of the devices.

Probing the dye-semiconductor interface in dye-sensitized NiO solar cells.

The development of p-type dye-sensitized solar cells (p-DSSCs) offers an opportunity to assemble tandem photoelectrochemical solar cells with higher efficiencies than TiO2-based photoanodes, pioneered by O'Regan and Grätzel [Nature 353, 737-740 (1991)]. This paper describes an investigation into the behavior at the interfaces in p-DSSCs, using a series of BODIPY dyes, BOD1-3. The three dyes have different structural and electronic properties, which lead to different performances in p-DSSCs. We have applied photoelectron spectroscopy and transient absorption spectroscopy to rationalize these differences. The results show that the electronic orbitals of the dyes are appropriately aligned with the valence band of the NiO semiconductor to promote light-induced charge transfer, but charge-recombination is too fast for efficient dye regeneration by the electrolyte. We attribute this fast recombination, which limits the efficiency of the solar cells, to the electronic structure of the dye and the presence of Ni3+ recombination sites at the NiO surface.

Synergistic Effect of Alkyl Chain Barriers on Heteroleptic Ruthenium Dyes and Co3+/2+ Complex Mediators for Reduced Charge Recombination in Dye-Sensitized Solar Cells

The performance of photoelectrochemical solar cells using heteroleptic Ru dyes paired with Co3+/2+ electrolytes is worse than their organic-dye-based analogues. Previous studies point to the import...

Effect of deposition time on photoelectrochemical performance of chemically grown Bi2Se3-sensitized TiO2 nanostructure solar cells

This paper explore the ability of bismuth selenide (Bi2Se3) as an alternative light sensitizer for photoelectrochemical (PEC) solar cell. Herein, we applied novel chemical route, namely, chemical bath deposition (CBD) for growth of Bi2Se3 nanoparticles over spin-coated TiO2 at room temperature. The structural, surface morphological, and optical properties of TiO2/Bi2Se3 films are systematically studied. The deposition time for the growth of Bi2Se3 using CBD can enable to tune the size of Bi2Se3 nanoparticles over porous TiO2 which significantly influences the physical properties of resultant heterostructure. The potential of Bi2Se3 nanoparticles in PEC solar cell is demonstrated by preparing FTO|TiO2|Bi2Se3|polysulphide electrolyte|carbon-coated FTO device structure and tested with current density–voltage (J-V) and electrochemical impedance spectroscopy (EIS) measurements. The result presented in this study established that the photoconversion efficiency and electron life time of device are affected by deposition time for Bi2Se3 using CBD. The J-V measurement done with above-proposed devices shows maximum photoconversion efficiency around 0.152% for 20 min deposited Bi2Se3.

Designing a Transparent CdIn2 S4 /In2 S3 Bulk-Heterojunction Photoanode Integrated with a Perovskite Solar Cell for Unbiased Water Splitting.

The integration of photoelectrochemical photoanodes and solar cells to build an unbiased solar-to-hydrogen (STH) conversion system provides a promising way to solve the energy crisis. The key point is to develop highly transparent photoanodes, while its bulk separation efficiency (ηsep. ) and surface injection efficiency are as high as possible. To resolve this contradiction, first a novel CdIn2 S4 /In2 S3 bulk heterojunctions in the interior of nanosheets is designed as a photoanode with high transparency and an ultrahigh ηsep. up to 90%. Furthermore, decorating the ultrathin amorphous SnO2 layer by atomic layer deposition, the surface oxygen-evolution kinetics of the photoanode are increased significantly. As a result, the onset potential of the photoanode shifts negatively to 0.02 V vs RHE, and the photocurrent density boosts to 2.98 mA cm-2 at 1.23 V vs RHE, which is ten times higher than that of pristine CdIn2 S4 . Such a high-performance photoanode enables the integrated metal sulfide photoanode-perovskite solar cell system to deliver a STH conversion efficiency of 3.3%.

Investigating the photovoltaic performance of surfactant-assisted MoBi2Se5 thin films

Molybdenum bismuth selenide (MoBi2Se5) has been proved to be a promising material for photoelectrochemical solar cell application. As MoBi2Se5 thin films are more corrosion resistant than bismuth (III) selenide (Bi2Se3) thin films, MoBi2Se5 can also be used as a buffer layer due to its distinctive optostructural properties. In this study, the authors synthesized surfactant-assisted nanostructured MoBi2Se5 thin films by using a cost-effective chemical route – namely, the arrested precipitation technique. The synthesized thin films were analyzed for optostructural, surface morphological, compositional and photovoltaic applications using the X-ray diffraction (XRD) technique, ultraviolet–visible spectroscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy, and their photoelectrochemical solar cell performance was checked. The nanocrystalline nature of MoBi2Se5 thin films was confirmed from the XRD patterns. An increment in the optical bandgap energy was observed with surfactant mediation. The surface morphology of MoBi2Se5 changed from spherical to spongy-ball-like nanofibrous surface morphology after surfactant assistance. Furthermore, both the as-synthesized and surfactant-assisted MoBi2Se5 thin films showed photoelectrochemical solar cell applicability.

One-step hydrothermally assisted synthesis of CuZnSe thin film: photovoltaic application

Herein, a one-step hydrothermal route was directly employed to synthesize copper-doped zinc selenide (CuZnSe) thin film. The synthesized CuZnSe thin film was analyzed for its optostructural, morphological, compositional and photovoltaic characteristics. The optical studies revealed that the deposited CuZnSe thin film exhibited a direct allowed type of optical transition with 2·32 eV bandgap energy. The structural studies demonstrated the formation of a pure cubic CuZnSe crystal phase structure with 57 nm crystallite size. The low- and high-resolution scanning electron microscopy images showed the formation of nanospherical surface morphology. The energy-dispersive spectroscopic analysis confirmed the presence of the elements copper (Cu), zinc (Zn) and selenium (Se) in the deposited thin film. Lastly, the photoelectrochemical properties were investigated using a two-electrode configuration in the dark and under light illumination from a 500 W tungsten filament lamp with an intensity of 30 mW/cm2 on an electrochemical workstation. In the dark condition, the current density–voltage (J–V) curve shows diode-like rectifying characteristics, and under illumination of light, it shows photovoltaic performance with 0·73% photoconversion efficiency. The photovoltaic results indicated that employment of one-step hydrothermally synthesized CuZnSe thin films has great potential for fabrication of photoelectrochemical solar cells.

Synthesis and Computational and Experimental Investigations of a para-Nicotinic Acid-Bridged Dirhenium(I) Dimer Complex.

The Re(I) dimer complex, [fac(CO)3(phen)Re1-N(py)COORe2(phen)fac(CO)3]+ (py = pyridine; phen = 1,10-phenanthroline), contains two different Re(I) centers 9.3 Å apart, one with a nitrogen donor and the other with an acetate donor from the bridging isonicotinate ligand. The complexes were characterized by 1H NMR, UV–vis, fluorescence, and IR spectroscopy, elemental analysis, and single-crystal X-ray diffraction. The absorption and emission properties of the dimer dominated by charge transfer transitions are analyzed with respect to those of the monomers, [fac(CO)3(phen)Re-N(pyCOOCH3)]+ and [fac(CO)3(phen)ReOOCCH3]. Spectral comparison of these three complexes results in the unexpected finding that the dimer emission (575 nm) occurs near that of the nicotinate-containing monomer (580 nm) rather than near the lower energy-emitting state (650 nm) of the acetate-containing monomer. Density functional theory (DFT) calculations elucidate this unusual emission behavior. The geometries of the dimer and two monomers are optimized in the singlet ground and lowest-energy triplet excited states (LLTS’s) to interpret absorption and emission behaviors, respectively. The singlet excited states calculated using time-dependent DFT correlate well with the absorption spectra in the lowest-energy and other major electronic transitions. The energy gaps and low-lying singlet excited states of the dimer are close to those of the acetate-containing monomer. The lowest-energy Franck–Condon triplet excited state of the dimer arising from electronic transitions localized on the acetate moiety is unstable. The next higher Franck–Condon triplet excited state arises from long-range charge transfer transition, and its energy is close to that of the nicotinate-containing monomer. Optimization of the dimer LLTS yields a stable state based on a long-range charge transfer transition involving occupied orbitals partially localized on the bridging nicotinate moiety. The LLTS energies of the dimer and nicotinate-containing monomer are in very good agreement as are the emission energies of these complexes. The correlated spectroscopic and computational results corroborate to the understanding of charge transfer states and transitions toward the development of photosensitive compounds for photoelectrochemical solar energy conversion cells.

ZnCdS thin film chalcogenide by chemical bath deposition method

Chalcogenide ZnCdS thin films preparation by chemical bath deposition method is currently considerable interest because it is relatively inexpensive, simple and large area deposition technique. Different substrates are used since these are low temperature process which avoids oxidation and corrosion behavior of substrate. Photoelectrochemical solar cells, photoconductors, detectors, sensors, etc. are some of the applications of chalcogenide ZnCdS thin films. The effect of zinc content on structural, morphological and optical properties have been reviewed. Further, the changes occurred after annealing of the film at different temperatures and different time have also been incorporated and discussed in this article. In the present review, we have described in detail chemical bath deposition method for chalcogenide ZnCdS thin films. The method is capable of yielding good quality thin films. Their preparative parameters, structural, morphological and optical properties have been discussed in this review article.

Wide Band Gap Chalcogenide Semiconductors.

Wide band gap semiconductors are essential for today's electronic devices and energy applications because of their high optical transparency, controllable carrier concentration, and tunable electrical conductivity. The most intensively investigated wide band gap semiconductors are transparent conductive oxides (TCOs), such as tin-doped indium oxide (ITO) and amorphous In-Ga-Zn-O (IGZO), used in displays and solar cells, carbides (e.g., SiC) and nitrides (e.g., GaN) used in power electronics, and emerging halides (e.g., γ-CuI) and 2D electronic materials (e.g., graphene) used in various optoelectronic devices. Compared to these prominent materials families, chalcogen-based (Ch = S, Se, Te) wide band gap semiconductors are less heavily investigated but stand out because of their propensity for p-type doping, high mobilities, high valence band positions (i.e., low ionization potentials), and broad applications in electronic devices such as CdTe solar cells. This manuscript provides a review of wide band gap chalcogenide semiconductors. First, we outline general materials design parameters of high performing transparent semiconductors, as well as the theoretical and experimental underpinnings of the corresponding research methods. We proceed to summarize progress in wide band gap (EG > 2 eV) chalcogenide materials-namely, II-VI MCh binaries, CuMCh2 chalcopyrites, Cu3MCh4 sulvanites, mixed-anion layered CuMCh(O,F), and 2D materials-and discuss computational predictions of potential new candidates in this family, highlighting their optical and electrical properties. We finally review applications-for example, photovoltaic and photoelectrochemical solar cells, transistors, and light emitting diodes-that employ wide band gap chalcogenides as either an active or passive layer. By examining, categorizing, and discussing prospective directions in wide band gap chalcogenides, this Review aims to inspire continued research on this emerging class of transparent semiconductors and thereby enable future innovations for optoelectronic devices.

Sustainable Organic Dyes from Winemaking Lees for Photoelectrochemical Dye-Sensitized Solar Cells

During the last two decades, Dye Sensitized Solar Cells (DSSCs) have received a great deal of attention as a promising, low-cost alternative to conventional silicon photovoltaic devices. Natural dye molecules can be used as a sensitizer for their low cost, good light absorbance, easy preparation process, and biodegradability. In this study, dyes were obtained from wine lees, the last by-product of winemaking process, supplied by a venetian winery (Italy). Polyphenols, like tannins and anthocyanins, which were extracted from winemaking lees, were adsorbed on a nanostructured ordered mesoporous titanium dioxide, previously treated at different temperatures (400–600 °C). Both dyes and titania semiconductor samples were studied with different techniques. The tests were carried out on prototypes to evaluate the cell power and the photocurrent generated under simulated solar light irradiation. The obtained solar energy conversion efficiencies are comparable to those that were reported in literature by using organic dyes extracted from vegetables, fruits, and plants. It is significant that these dyes are largely available and cost effective, since recovered from a waste otherwise to be disposed of, opening up a perspective of feasibility for inexpensive and environmentally friendly dye solar cells to generate green electricity and transforming agri-food waste into a resource.

Plasmon-enhanced photoelectrochemical water splitting by InGaN/GaN nano-photoanodes

It has been extensively focused on the development of photoelectrochemical (PEC) solar water splitting cells due to the urgent need for clean energy. In this study, InGaN/GaN multiple quantum wells (MQWs) nanorods (NRs) PEs are purposely designed with coupled plasmonic metal (Ag–Au core–shell nanowires) for high efficiency PEC water splitting, aiming for enhancing visible light absorption and carrier kinetic energy. By means of self-organized Nickel island patterning and ICP dry etching with proper depths, the photocurrent density of InGaN/GaN nano-photoanodes in NaCl solution can be significantly enhanced from 0.74 mA cm−2 to 1.4 mA cm−2 at 1.5 V versus RHE (reversible hydrogen electrode). Furthermore, by decorating plasmonic metal into the InGaN/GaN NR arrays, the PEC water splitting performance can reach a maximum photocurrent of 1.77 mA cm−2 at 1.5 versus RHE. Such improvement is mainly attributed to the synergistic effects of the visible light absorption of MQWs and the generation of surface plasmon resonance (SPR). The approach of plasmon-enhanced nanostructure with the III-nitride based nano-PEs will accelerate the developments of visible light photocatalysts for PEC solar cells.

Fabrication and Characterization of ZnS based Photoelectrochemical Solar Cell

Fabrication and Characterization of ZnS based Photoelectrochemical Solar Cell

Optimization and comparative evaluation of optoelectronic properties of hydrothermally synthesized CdIn2Te4 thin films: PEC performance

Herein, hydrothermal route was directly employed to synthesize Indium doped CdTe nanocrystalline thin films. The influence of In doping on the optical, structural, morphological and photoelectrochemical solar cell properties have been investigated. The optical absorption study illustrates that, maximum absorption was observed in between 500–700 nm with decrease in band gap energy from 1.47 to 1.35 eV as function of In doping. Structural analysis reveals that, transition in crystal structure from hexagonal to tetragonal on In doping in CdTe. Morphological analysis demonstrates that, evolution of 1-D nanowire like morphology in CdIn2Te4 thin film. Compositional analysis confirms the presence of Cd, In and Te elements in CdIn2Te4 thin film with stoichiometric atomic percentage. X-ray photoelectron spectroscopy (XPS) analysis confirms that, presence of Cd, In and Te ions in its valence states of Cd2+, In3+ and Te2− respectively. Current density-voltage measurement illustrates that, CdIn2Te4 photocathode shows improved PEC performance with photoconversion efficiency 2.84%. The improved photovoltaic performance of In doped CdTe photocathode was explained in detail with the help of Nyquist plots and corresponding circuit model of the electron impedance spectra.