Photoelectrochemical Solar Cells Research Articles

Flexible Single‐Layer Fabric‐Based Co‐Laminar Flow Photosynthetic Microbial Fuel Cell

AbstractIn this study, textile‐based microbial photoelectrochemical solar cells are developed for flexible electronic device applications. Configuration of the self‐pumping microfluidic channel without a proton exchange membrane is adopted to miniaturize the biophotovoltaic device. The microchannel region of the miniature device is patterned by silk screen printing using a body‐friendly Ecoflex to maintain the flexibility of the fabric substrate. Gold nanoparticle biosynthesized Synechocystis sp. PCC 6803 biocatalyst, supercapacitive ternary nanocomposite anode, and solid‐state Ag2O oxidant are used to enhance the biosolar cell performance. A maximum current density of 135.1 µA cm−2 and peak power density of 14.1 µW cm−2, which are higher than previous textile‐based microbial fuel cells, are achieved in the presence of light. The monolayer fabric‐based biosolar cell has a stable performance up to 100 and 20 cycles of stretching and twisting, respectively. The presented new platform of flexible microbial solar cells offers the development possibility of self‐sustaining wearable electronics.

Comprehensive analysis of the performance of a microfluidic photoelectrochemical solar cell with heat exchanger

A dye-sensitized solar cell (DSSC) is a type of photoelectrochemical cell that converts sunlight directly into electricity using a photoanode with a dye-sensitized, nonporous semiconductor layer. This study investigates the impact of integrating microfluidic capabilities into DSSCs, resulting in a flow-cell configuration that introduces new electrical characteristics without compromising its performance. The primary goal of the work was to define and determine the values of heat, mass, and charge transport resistances, and to explore their relationships with the cell’s current–voltage characteristics, temperature, light intensity, and spectra. We employed both experimental methods and computational fluid dynamics using the Lattice-Boltzmann solver to analyze the cell’s dynamics. A novel multilayered microfluidic DSSC (µDSSC) was designed, featuring an innovative “gapless” configuration with a photoactive surface area exceeding 7 cm2, integrated directly with a microfluidic heat exchanger. This configuration allowed the µDSSC to achieve a power conversion efficiency (PCE) of at least 6 % under standard test conditions, with a fill factor reaching up to 68 %. By gradually covering the cell surface, the impact of series resistance (Rs) on PCE was minimized, enabling a maximum PCE of 19–22 %. A new integral definition of the fill factor (IFF) was proposed, which accurately describes the performance of cells constrained by ion mass transport resistance. For the gapless µDSSC, the IFF ranged from 58 % to 88 %. Additionally, we introduced a maximum cell efficiency (MCE) parameter to represent the cell’s efficiency at the theoretical limit of Rs = 0, determined to be 20.7 % for the gapless µDSSC. This MCE value is specific to the cell and is independent of the illuminated surface area and incident light intensity. The thermal efficiency of µDSSC cells is generally limited by heat conduction through the multilayer structure, but at practical cell surface temperatures of 50–80 °C, this limitation is 3 to 6 times less significant than the limitation imposed by the maximum solar energy flux reaching the cell surface. The integration of microchannels into the cell led to a 58 % reduction in hydraulic resistance along the main flow direction. While electrolyte flow typically reduces efficiency in wide-gap DSSCs, the gapless configuration minimizes mass transport resistance, ensuring that fluid flow does not adversely affect the performance of gapless µDSSCs.

Low‐Temperature Synthesis of Stable CaZn2P2 Zintl Phosphide Thin Films as Candidate Top Absorbers

AbstractThe development of tandem photovoltaics and photoelectrochemical solar cells requires new absorber materials with bandgaps in the range of ≈1.5–2.3 eV, for use in the top cell paired with a narrower‐gap bottom cell. An outstanding challenge is finding materials with suitable optoelectronic and defect properties, good operational stability, and synthesis conditions that preserve underlying device layers. This study demonstrates the Zintl phosphide compound CaZn2P2 as a compelling candidate semiconductor for these applications. Phase‐pure, ≈500 nm‐thick CaZn2P2 thin films are prepared using a scalable reactive sputter deposition process at growth temperatures as low as 100 °C, which is desirable for device integration. Ultraviolet‐visible spectroscopy shows that CaZn2P2 films exhibit an optical absorptivity of ≈104 cm−1 at ≈1.95 eV direct bandgap. Room‐temperature photoluminescence (PL) measurements show near‐band‐edge optical emission, and time‐resolved microwave conductivity (TRMC) measurements indicate a photoexcited carrier lifetime of ≈30 ns. CaZn2P2 is highly stable in both ambient conditions and moisture, as evidenced by PL and TRMC measurements. Experimental data are supported by first‐principles calculations, which indicate the absence of low‐formation‐energy, deep intrinsic defects. Overall, this study shall motivate future work integrating this potential top cell absorber material into tandem solar cells.

Optimization of CdSe Thin-Film Photoelectrochemical Cells: Effects of NaOH/Na2S/S Redox Couple Concentration and Activity on Cell Efficiency

This study investigates the relationships among redox couple activity, electrolyte concentration, and efficiency in CdSe thin-film photoelectrochemical solar cells. A CdSe photo-electrode was prepared using the electro-depositing technique to produce well-staged layering of CdSe, followed by chemical bath deposition to produce a layer with an acceptable thickness to absorb enough photons to create a suitable amount of photocurrent. The CdSe photo-electrochemical cell was tested under various concentrations of a NaOH/Na2S/S electrolyte solution. The results showed that the activity of the redox couple greatly affected the efficiencies of the solar cells. Correlation plots between ionic strength and PEC efficiency with the Debye–Hückel equation yielded an R² value of 0.96, while those between ionic strength and photocurrent density had an R² value of 0.92. The correlation between concentration and PEC efficiency was much weaker. This paper highlights how optimal ionic activity increases the performance of photoelectrochemical solar cells, which consequently improves the conversion efficiency of solar energy.

Influence of electrodeposited Cu2ZnSnS4 films for the reduction of 4-nitrophenol through electronic relay approach and serve as photoelectrode in PEC device

We explore the possibility of thin film Cu2ZnSnS4 (CZTS) as an effective catalyst for the reduction of 4-nitrophenol to 4-aminophenol in presence of NaBH4 through electronic relay process with the rate constant of 0.20 min−1, also as photoelectrode material for low-cost photoelectrochemical solar cells. Cu2ZnSnS4 thin films with thickness of ∼ 2 μm have been synthesized by an electrochemical approach. The electrochemical bath contained an aqueous solution of Cu(NO3)2·3H2O, Zn(NO3)2.6H₂O, SnC2O4 and Na2S2O3 with Citric acid as a chelating ligand at an optimum pH∼3.65. The morphology, composition, and optical properties were characterized by XRD, FE-SEM, HR-TEM, UV–Vis, FT-IR, and EPR analysis. The growth kinetics of CZTS have been invested with different time intervals, also changes of band gaps of deposited material have been noticed. Cyclic voltammetry of the electrode is done to predict the co-deposited system in the quaternary semiconductor in 0.1 M KCl as supporting electrolyte. The deposited Kesterite phase of CZTS has been systematically investigated to serve as an effective counter electrode material for photoelectrochemical (PEC) energy conversion in 0.5 M polysulfide (Na2Sx) redox couple which showed an efficiency of ∼ 4.395 %. The development of a facile and green chemical route for the preparation of a well crystallized and stable CZTS photoelectrode still remains a challenge.

Thymus schimperi Ronniger plant flower extract dye-sensitized solar cells

The demand for energy is greatly increasing due to the world’s population growth and technological advancement. Natural dye-sensitized solar cells are attracting research as an alternative and renewable energy source due to their simple preparation technique, availability, cost effectiveness and environmental friendliness. In the present work, we have successfully fabricated dye-sensitized solar cells (DSSCs) from Thymus schimperi Ronniger plant flowers for the first time. The solvents used for extraction of the flower dye were deionized water and its mixture with ethanol. The T. schimperi Ronniger flower extract dye solutions and sensitized photoanodes were characterized by Fourier transform infrared and ultraviolet–visible techniques. The crystallinity of TiO2 films was analyzed by x-ray diffraction, and the films showed pure anatase phase behavior. The photoelectrochemical solar cell performance parameters, such as short circuit current density, open circuit voltage, fill factor and efficiency, were evaluated from current density–voltage measurements using a Keithley 2450 source meter. DSSCs sensitized with dye solution extracted by a mixture of water and ethanol showed better performance (1.37%) than those sensitized with dye solution extracted by deionized water alone (1.02%).

Novel Phenothiazine and Coumarin based Sensitizers: Design, Synthesis and Photoelectrochemical Application by Anchoring on CdS Nanowires

Novel metal-free organic dyes (E)-2-cyano-3-(10-(prop-2-yn-1-yl)-10H-phenothiazin-3-yl)acrylic acid (PPC) and (E)-2-cyano-3-(10-((1-((7-methyl-2-oxo-2H-chromen-4-yl)methyl)-1H-1,2,3-triazol-4-yl)methyl)-4a,10a-dihydro-10H-phenothiazin-3-yl)acrylic acid (PCTC) was synthesized and then anchored to 1D cadmium sulfide nanowires (1D CdS NWs) for application in photoelectrochemical dye-sensitized solar cell (DSSC). The 1D CdS nanowires were interconnected into a nanonetwork using solution chemistry in a straightforward and efficient manner. The UV-visible spectroscopy, cyclic voltammetry and density functional theory (DFT) were effectively employed to analyze the characteristics of PPC and PCTC. The sensitizer-anchored CdS nanowires have a broader range of light absorption in the UV-visible spectrum compared to bare CdS nanowires. The complete device has the assembly FTO, compact CdS, CdS nanowires, synthesized dye and counter electrode. In photovoltaic assessment, the PCTC and PPC devices yield 3.19 and 3.04 times, respectively, more efficiency than naked CdS nanowires under conventional sunshine illumination (100 mW/cm2, AM 1.5G). The obtained results provide strong evidence supporting the presence of rising external quantum efficiency (EQE) and show a high level of consistency with the optical tests.

The stability improvement of photoelectrochemical solar cells with Bi2S3 quantum dots sensitized photoanodes

Bi2S3, Bi2MoO6 and TiO2 composite photoanodes were fabricated using three different preparation routes to improve its photoelectrochemical (PEC) stability. The microstructure of three photoanodes are distinct significantly according to the results of XRD, SEM and TEM. The ordered TiO2 nanorod arrays (NRAs) and thinner Bi2MoO6 sheet crystals in flower-ball structure facilitate carrier transport and suppresses electron-hole recombination efficiently. The results of PEC tests indicate that the photoanode with Bi2MoO6 sheet crystals in flower-ball structure and TiO2 NRAs shows significant enhancement in PEC performance stability due to its ordered microstructure facilitating carrier transport and transfer and also good adherence of photoanode layer on FTO glass substrate. This photoanode in Bi2S3 quantum dots/Bi2MoO6@TiO2 NRAs structure exhibits satisfactory properties, achieving a PEC stability of 86.41% after 48 h.

Fabrication of single-step novel synthesis of ZnCd(S0.5Se0.5)2 thin films for photoelectrochemical (PEC) cell application

In our study, we use a new method called the arrested precipitation technique (APT) to create CdZn(SSe)2 (CZSS) thin films. We obtain samples at different deposition times, ranging from 2.5 to 4 h, and analyze the effects of deposition time on the opto-structural, morphological, compositional, and photoelectrochemical (PEC) solar cell properties. As a result, we find that the band gap energy increases from 2.366 to 2.60 eV with prolonged growth time, as shown by UV–Vis spectra. X-ray diffraction (XRD) analysis confirms that the crystal structure is hexagonal, with the crystallite size increasing from 76 to 93 nm. The dislocation density and microstrain, determined by the Scherrer formula, decrease from 1.72 to 1.14 lines m−2 and from 4.75 × 10−3 to 3.87 × 10−3 (lines m−2), respectively. These results are validated using the Williamson-Hall (WH) plot and size-strain plot. The average grain size, evaluated using the standard scale bar method in scanning electron microscopy (SEM), ranges from 80 to 150 nm across CZ1 to CZ4 samples. Transmission electron microscopy (TEM) images of CZ4 and CZ2 reveal particle sizes of 101 nm and 87 nm, respectively, while selected area electron diffraction (SAED) patterns confirm the polycrystalline nature of the material. Energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) analyses confirm the presence of Cd, Zn, S, and Se elements in their intended stoichiometry. Notably, CZSS photoelectrodes deposited over 4 h show better performance in Photoelectrochemical cells (PEC), achieving the highest photoconversion efficiency (ɳ) at 2.33 %, as evidenced by J-V measurements.

Advancing Photoelectrochemical Systems: Unleashing the Remarkable Performance of In : SnO2/Nd4In5S13 for Sustainable Energy Applications

AbstractNeodymium Indium sulphide (Nd4In5S13) photoactive electrode was produced by spin‐coating for photoelectrochemical cell. The photoactive electrode is analysed for its crystalline, structural and elements makeup in addition to its optical and electrical responses. A 56 nm sized orthorhombic crystallite was found and geometrical compact structures were observed. The presence of chief elements with core levels of In3d, Nd4d and S2p were detected. The bandgap energy was found to be 4.1 eV. Electrochemical investigations were performed to evaluate the photoactive efficiency of the electrode. Photo‐cyclic voltammetry present a specific capacitance under illumination to be 570 Fg−1, as contrasting to 481 Fg−1 when in dark. A photocurrent density of 282 mA cm−2 was obtained from photo‐linear sweep voltammetry. It had also been discovered that the transient chronoamperometry provided a photocurrent density of 46.1 mA cm−2. Whereas electrical impedance spectroscopy presented internal resistance (Rs) to be 232 Ω. All scan rates show an increase in the specific capacitance of photo‐electrode when illuminated. The research created an effective photo‐electrode for renewable energy structures. It can be posited that the study presented a pragmatic photoelectrode, which had the potential to be employed in sustainable energy frameworks, including but not limited to photovoltaics, supercapacitors, and photoelectrochemical solar cells.

Fabrication of Dye Sensitized Solar Cell using Baccate (Berry) and Citrullus Lanatus (Water Melon) as Dye

The DSSC (dye-sensitized solar cell) is a photo electrochemical solar cell using redox mediator to transport electrons and become an attractive alternative to the widely used Si-based solar cell due to its low processing cost, ease of fabrication, moderate efficiency, and economical friendly. In this work DSSCs were fabricated using berry and watermelon as dye. Our results shows that DSSC with berry have higher efficiency than one with watermelon. The open circuit voltage (Voc), short circuit current, fill factors (FF), maximum power point (PMPP) and efficiency (η) for these cells were obtained and analyzed. The efficiencies for these cells are below prohibitive efficiency and this could be as a result of using ordinary glass because there were no availability of FTO. Further research work is ongoing with the use of FTO and comparative analysis will be carry out.

Novel 1,2,4-triazole sensitizers using N-arylsydnone as Synthon: Synthesis, Spectral, electrochemical, DFT and photovoltaic properties

Two novel 1,2,4-triazolone derivatized triphenylamine (TPA) and phenothiazine (PTZ) based metal-free organic dyes have been designed, synthesized and anchored on 1D CdS nanowires to serve as photoelectrochemical (PEC) dye-sensitized solar cells (DSSCs). Solution chemistry is employed simply and efficiently to link cadmium sulfide nanowires (CdS NWs) into a nano-network. Optical, electrochemical and density functional theory (DFT) have been well utilized to examine the properties of synthesized dyes (TPA and PTZ). In the visible range, sensitizer-anchored CdS NWs exhibit a wider region of light absorption referenced to naked CdS NWs. Comprehensive photovoltaic assessment showed that TPA and PTZ devices respectively showed IPCE 3.02 and 3.13 times more efficient than bare CdS NWs under standard sunlight (100 mW/cm2, AM 1.5G) illumination. The collected findings offer solid evidence for the existence of increasing external quantum efficiency (EQE) and exhibit good agreement with the optical experiments.

Efficiency Improvement of Photoelectrochemical Solar Cell Applications by Using Ternary Hybrid MoS2/g-C3N4/Cu2O

In this paper, molybdenum disulfide MoS2 was hybridized with graphene carbon nitrite (g-C3N4) and Cu2O in order to enhance the photoelectrochemical (PEC) activity and increase the light absorption range of Cu2O thin film. The melamine powder was poured in an empty container and then heated in a furnace to attain the powder. The ternary hetero-epitaxial growth was achieved by growing of MoS2/g-C3N4 on the Cu2O hybrid by a partial thermal oxidation process. The characteristics of MoS2/g-C3N4/Cu2O hybrid film were investigated through XRD, FT-IR and photoelectronchemistry-related measurements. The PEC behavior of the ternary hybrid electrode was investigated using current-voltage test under illumination. The efficiency calculated from current-voltage test under illumination shows that the presence of graphene carbon nitrite and molybdenum disulphide within the film networks, despite its low content, could stimulate substantial improvement in maximum photoconversion efficiency from 0.036% to 0.33%. This improvement is attributable to the enhancement of the electron-transferring proficiency upon the insertion of g-C3N4 and, MoS2 as confirmed by X-Ray Diffraction Analysis (XRD). The PEC test results signify that the photoelectrochemical activity of the MoS2/g-C3N4/Cu2O ternary hybrid is much higher than that of subtrate. The mechanisms accountable for the enhanced PEC behavior of the MoS2/g-C3N4/Cu2O ternary hybrid are discussed in detail.Keywords: Cuprous Oxide, J-V Characteristic, Hetero-structure, Photoelectrochemical, Thermal Oxidation.

Nano structured diatom frustules incorporated into TiO2 photoelectrodes to enhance performance of quasi-solid-state dye-sensitized solar cells

Diatom frustules are incorporated into multilayer photoelectrodes intending to enhance efficiency in dye-sensitized solar cells utilizing their light interaction properties. A specific, but ubiquitous in all oceans, pennate-type diatom frustules were used to form the composite layers. Single, double, and triple-layer photoelectrodes were constructed with pure TiO2 (control measurements) as well as with a TiO2/diatom frustule composite. The electrodes were prepared using TiO2 nanoparticles of two sizes (13 and 21 nm) and were analyzed using UV visible absorption and XRD spectra. The morphology of frustules and electrodes were analyzed using scanning electron microscopy. The performance for each photoanode configuration was measured by assembling photoelectrochemical solar cells fabricated with a Pt counter electrode and a gel polymer electrolyte that excludes volatile solvents. The efficiency of the control cell is 3.37%. After replacing the topmost TiO2 layer with a TiO2/diatom frustule composite layer, efficiency increases to 6.78%. This is an impressive efficiency enhancement of 101%. The short circuit current density of frustule-incorporated three-layer cells is 18.1 mA cm−1 while for the control cell it is 8.98 mA cm−1. The enhanced efficiency of cells made with TiO2/diatom frustule composite electrodes and a polyethylene oxide-based gel polymer electrolyte can be attributed to the improved light absorption by the photoanode due to optical scattering and light-trapping effects caused by the presence of diatom frustules. Frustules also can assist in enhancing dye adsorption by increasing the effective specific surface area of the composite photoelectrode due to their nanoporous structure.

Transferable Highly (001) Oriented Sb2Se3 Nanorod Films on Flexible Substrates for Innovative Optoelectronic Devices

AbstractThin films of antimony chalcogenides, Sb2X3 (X = S, Se, or SxSe1−x), comprised of (001) oriented nanorods are highly desirable for optoelectronic applications owing to their light trapping capacity and highly efficient charge transport along the optimally aligned quasi‐1D (Sb4X6)n ribbons. Here, highly (001) oriented Sb2Se3 nanorod (Sb2Se3NR) layers are obtained via a novel template growth method, and transfer these layers to functional substrates via a polymer‐assisted technique. Transferable layers overcome the current challenges associated with achieving oriented growth directly on the desired substrate. Using a combination of a low‐temperature processable SnO2 nanoparticle transport layer and encapsulation/etching techniques photodetector devices are fabricated with excellent electrical contact. The optimized transferred devices show broad range photoresponse with signal‐to‐noise ratios up to 105 and responsivities reaching 0.96 mA W−1. Importantly, access to low‐temperature processing enables the fabrication of flexible devices. Based on this platform, a proof‐of‐concept self‐powered flexible heart rate monitor is fabricated. The achievement of transferable Sb2Se3NR layers introduced in this work is expected to be readily applicable to generate new (001) Sb2Se3 device architectures that may otherwise not be achievable via direct deposition, with application in photoelectrochemical water splitting, battery electrodes, and solar cells.

(Invited) Solar Flow Batteries: Integrated Photoelectrochemical Solar Energy Conversion and Redox Flow Battery Systems

Due to the intermittent nature of sunlight, practical solar energy utilization systems demand both efficient solar energy conversion and inexpensive large scale energy storage. We have developed hybrid solar-charged storage devices called solar flow batteries (SFBs) that integrate photoelectrochemical solar cells with redox flow batteries (RFBs). In these devices, photoexcited carriers collected at the semiconductor-liquid electrolyte interface convert the redox couples to charge up the RFB without external electric bias; which can be discharged to generate the electricity when needed. By matching various silicon solar cells and tandem III-V solar cells (Chem 2018, 4, 2644) with various organic redox couples and optimizing the SFB device design, we improved their round trip solar-to-output electricity efficiency (SOEE) and eventually achieved a record SOEE of 20% with a 500-hour lifetime using high performance tandem perovskite/silicon solar cells (Nature Mater. 2020, 19, 1326). The design principles and the quantitative analysis model for voltage matching solar cells with RFBs (Acc. Chem. Res. 2020, 53, 2611) light up the pathways for achieving even better performance and stability yet maintaining a low cost, which would make these SFBs practical for standalone solar energy conversion and storage systems in remote off-grid locations.

Highly conducting flake-like CuS nanostructured counter electrode for photoelectrochemical solar energy conversion

Fabrication of platinum (Pt) free, low cost, environmentally friendly counter electrode is highly attractive for electrochemical solar energy conversion. In this report, highly conducting flake-like CuS nanostructured counter electrode has been prepared for photosensing study and semiconductor sensitized solar cell application. Flake-like CuS nanostructures were synthesized by sulfuration of CuO nanorods grown by hydrothermal process. Scanning electron microscopy and atomic force microscopy study confirmed the growth of flake-like CuS nanostructures on glass substrates. CuS nanoflakes were highly crystalline with hexagonal phase. The various electronic states of Cu and S in CuS nanoflakes were studied using X-ray photoelectron spectroscopy. Chemically grown CuS films were highly conducting and highest conducting film was obtained at 85°C growth temperature with sheet resistance ∼20.02±0.02Ω/sq. Photoelectrochemical solar cell (PEC) was fabricated using CdS decorated TiO2 nanorods as working electrode and CuS film as counter electrode. The short circuit current density, open circuit voltage and power conversion efficiency of the PEC device were found to be ∼4.8 A/m2, ∼0.38 V and ∼0.17%, respectively.

Hot carrier extraction from 2D semiconductor photoelectrodes

Hot carrier-based energy conversion systems could double the efficiency of conventional solar energy technology or drive photochemical reactions that would not be possible using fully thermalized, "cool" carriers, but current strategies require expensive multijunction architectures. Using an unprecedented combination of photoelectrochemical and insitu transient absorption spectroscopy measurements, we demonstrate ultrafast (<50 fs) hot exciton and free carrier extraction under applied bias in a proof-of-concept photoelectrochemical solar cell made from earth-abundant and potentially inexpensive monolayer (ML) MoS2. Our approach facilitates ultrathin 7 Å charge transport distances over 1cm2 areas by intimately coupling ML-MoS2 to an electron-selective solid contact and a hole-selective electrolyte contact. Our theoretical investigations of the spatial distribution of exciton states suggest greater electronic coupling between hot exciton states located on peripheral S atoms and neighboring contacts likely facilitates ultrafast charge transfer. Our work delineates future two-dimensional (2D) semiconductor design strategies for practical implementation in ultrathin photovoltaic and solar fuel applications.

In:SnO2/Yb2S3:Cu2S:ZnS: A Rare Earth Metal Sulfide‐Conjugated Transition Metal Sulfide Photoactive Electrode

Spin coating from a single source precursor is used to produce a transparent conductive electrode for a photoelectrochemical cell. Yb2S3:Cu2S:ZnS is discovered in the composite using X‐ray diffraction analysis with a crystallite size of 44 nm. Energy‐dispersive X‐ray analysis and X‐ray photoelectron spectroscopy reveal that the composite comprises Yb, Cu, Zn, and S with an optical bandgap of 2.49 eV. Electrical investigations in a photoelectrochemical cell are measured using cyclic voltammetry, linear sweep voltammetry, transient chronoamperometry (CA), and electrical impedance spectroscopy (EIS). Every experiment shows that the photocurrent density of the electrode is higher than when it is in the light. At all scan rates, light causes the photoelectrode's specific capacitance to increase. Specific capacitance is found to have a maximum value under illumination of 789 Fg−1 as opposed to 745 Fg−1 in the absence of a light source. The highest photocurrent density achieved by the electrode through CA is 23.5 mA. Rs value of 23.4 Ω is subsequently obtained by the EIS investigation. It might be stated that this work introduces a useful photoelectrode that can be used in renewable energy systems such as photovoltaics, supercapacitors, and photoelectrochemical solar cells.

Answering old questions with new techniques: Understanding performance-limiting factors in transition metal dichalcogenide photoelectrochemical solar cells

In the late 1970s and early 1980s, several research groups reported high-efficiency and stable photoelectrochemical solar cells based on transition metal dichalcogenides (TMDS; e.g., MoS 2 , WSe 2 , and MoSe 2 ) immersed in iodide/tri-iodide electrolytes. A consensus emerged that smooth crystals were necessary for high efficiency based on significant evidence that rough crystals with exposed edge sites produced lower photocurrents and fill factors. However, anecdotal observations in the literature hinted at significant performance variation among apparently smooth crystals with the possibility of highly active “hot” edge sites. This mini-review article is a case study on how spatially resolved photoelectrochemical techniques developed in the 2020s are answering old questions regarding the origin of performance variation in high efficiency n-type TMD|I – ,I 3 – |Pt photoelectrochemical solar cells.