Visible Region Of Solar Spectrum Research Articles

A Review on the Applicability of Luminescent Phosphors and Effective Positioning in Dye‐Sensitized Solar Cells for Enhanced Performance and Stability

The narrow range of solar light absorption facilitated by the photoactive organic dyes has been restricting the significant development, and large‐scale applications of dye‐sensitized solar cells (DSSC). The major problem that limits the power conversion efficiency (PCE) of DSSC is the limitations of the organic dyes (light absorbers in DSSC) to absorb beyond the visible region of solar spectrum that resulting in lower PCE (≈13%) as compared with the commercialized technologies. Hence, the focus on developing efficient strategies to harvest the ultraviolet and infrared light regions of the solar spectrum and effective conversion into the absorption limit of dyes and thereby increasing the device performance and stability is the emerging technological development in DSSCs. Rare earth ion‐doped upconversion (UC) and downconversion (DC) phosphors are the most promising solutions for the prevalent issues of the liquid junction solar cells. This review will focus on the emerging strategies for the PCE enhancement of DSSC with UC and DC materials. An exclusive review on the facile approach of simultaneous usage of both the UC and DC phosphors and the effective positioning of these spectral conversion phosphors, to achieve highly stable DSSCs with superior PCE is provided.

Natural sensitizer extracted from Mussaenda erythrophylla for dye-sensitized solar cell

In this study, a natural dye from the flowers of Mussaenda erythrophylla extracted separately in ethanol and de-ionized water was employed as a photosensitizer in DSSCs. The quantitative phytochemical analyses were performed on both extracts. The existence of flavonoids (anthocyanin) and chlorophyll a pigments in the ethanol extract of the dye was confirmed by the UV–Visible spectroscopy. The stability study performed on the said ethanol extract confirmed that the dye extracted in ethanol was stable in the dark and did not degrade for nearly 50 days. The presence of the dye molecules and uniform adsorption of them on the P25-TiO2 surface were confirmed by fourier transform infrared spectroscopy and atomic force microscopy, respectively. Moreover, the influence of dye concentration and pH on the optical properties of the dye was also studied. The natural dye extracted in ethanol was employed in DSSCs, fabricated by utilizing the said dye sensitized P25-TiO2 photoanodes, {I}^{-}/{I}_{3}^{-} electrolyte, and Pt counter electrode. Photovoltaic performances of the fabricated devices were determined under simulated irradiation with the intensity of 100 mWcm–2 using AM 1.5 filter. The device fabricated with the P25-TiO2 photoanode sensitized by the dye extracted in ethanol at pH = 5 exhibited the best power conversion efficiency (PCE) of 0.41% with the JSC of 0.98 mAcm–2 which could be attributed to the optimum light absorption in the visible region of solar spectrum by the chlorophyll a and anthocyanin molecules in the extracted natural dye.

Influence of Deposition Parameters for Cu2O and CuO Thin Films by Electrodeposition Technique: A Short Review

The transition metal oxide-based nanomaterial attracted researchers for its various applications due to its interesting physical, chemical, and optical properties. Copper oxide thin films with different oxidation states were prepared on various transparent, nontransparent nature conducting substrates from the acidic and alkaline medium by electrodeposition technique. The deposition parameters such as potential, bath temperature, solution pH, and deposition time determine the physical, chemical, and optical properties. The complexing agents such as sodium thiosulfate, lactic acid, citric acid, and triethanolamine determine the stability of cuprous and cupric ions in the deposited films. Optical properties reported that the deposited films have direct band gap value 1.3 and 3.7 eV represents the absorbance of the deposited films in the visible region of solar spectrum. The absorbance of light in visible region, good electrical conductivity, and various nanostructure morphologies with the environment-friendly constituents are the distinctive properties of copper metal oxides.

Synthesis of WO3/Ag3VO4 photocatalyst with enhanced visible light efficiency photocatalysis

WO3/Ag3VO4photocatalyst was synthesized for benefiting the visible region of solar spectrum for degradation of antibiotic pollutant. The prepared catalyst was characterized by using scanning electron microscope (SEM), X-ray diffraction (XRD), infrared spectroscopy (IR) and energy-dispersive X-ray spectroscopy (EDX). The photocatalytic performance of material was evaluated by the photoredution of degradation of Amoxicillin (AMX) antibiotic under visible light. Results show that the obtained WO3/Ag3VO4photocatalyst can significantly enhance photocatalytic activity in comparison with the pure WO3 and Ag3VO4. The enhanced photocatalytic activity of WO3/Ag3VO4 was predominantly attributed to the synergistic effect which increased visible-light absorption and facilitated the efficient separation of photoinduced electrons and holes.

Simple chemical route synthesized TiO2/Ag2S heterostructure towards efficient semiconductor sensitized solar cells

The efficient and inexpensive semiconductor sensitized solar cell (SSSC) device is fabricated based on TiO2/Ag2S photoanode, synthesized by chemically grown Ag2S nanoparticles over porous TiO2 at room temperature. The structural, optical, surface morphological and electrochemical performances of as deposited TiO2/Ag2S photoanode are systematically studied. The result designated that the tiny Ag2S nanoparticles are uniformly decorated on porous TiO2 thin film and efficiently extended their photo response in visible region of solar spectrum. Furthermore the paper explored the potential of Ag2S nanoparticles as a sensitizer in SSSC by constructing sandwich type device structure. The electrochemical and photovoltaic performance of the proposed architecture clearly reveals the charge transportation as well as device grade performance is significantly influenced by number of deposition cycles. The maximum photo conversion efficiency of 1.3% is achieved under illumination of simulated sunlight.

Photocatalytic and Photoluminescence Studies of La, Ce, and Dy Co-doped ZnO Nanoflowers

In the present work, ZnO nanoparticles were doped with varying concentration of lanthanum (La), cerium (Ce), and dysprosium (Dy) using a simple and cost-effective co-precipitation approach at low temperatures. The resulting powders were calcined at 500 °C for 1 h using a muffle furnace, to produce La, Ce, and Dy-co-doped ZnO nanoparticles with varying stoichiometry, viz. (Zn0.97La0.01Ce0.01Dy0.01O, Zn0.94La0.02Ce0.02Dy0.02O, Zn0.91La0.03Ce0.03Dy0.03O, Zn0.88La0.04Ce0.04 Dy0.04O, and Zn0.85La0.05Ce0.05Dy0.05O). This is a simple approach for doping and does not require a complex equipment, harmful chemical, or sophisticated machinery. The synthesized powders were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) for studying the structure, purity, and grain morphology. Compositional study was done using EDS (SEM/EDS Hitachi 3600 N). The average crystallite size was calculated using XRD and was found to be 35 nm, and it also indicated a hexagonal wurtizite structure with no secondary peaks. A change in morphology from nanorods to nanoflowers was observed as the concentration of dopants increased. Photoluminescence (PL) spectra indicated a redshift in the absorption edge toward the visible region of solar spectrum and this was further confirmed by diffuse reflectance spectra (DRS). The photocatalytic properties of undoped and La, Ce, and Dy-co-doped ZnO nanoparticles were observed by examining the photodegradation of Rhodamine B dye under UV irradiation. The elimination of dye color indicated the total degradation of organic molecule. The results revealed that ZnO photocatalyst with La, Ce, and Dy co-dopant concentration Zn0.85La0.05Ce0.05Dy0.05O exhibited the best photocatalytic performance (95%) as compared to undoped ZnO. The improved photocatalytic performance can be attributed to the increased surface oxygen vacancies and adsorption capacity. The delay in recombination of charge carriers due to creation trap states in the bandgap of ZnO further improves the photocatalytic performance of doped samples.

High-throughput screening to modulate electronic and optical properties of alloyed Cs2AgBiCl6 for enhanced solar cell efficiency

The lead-free double perovskite material (viz. Cs2AgBiCl6) has emerged as an efficient and environmentally friendly alternative to lead halide perovskites. To make Cs2AgBiCl6 optically active in the visible region of solar spectrum, band gap engineering approach has been undertaken. Using Cs2AgBiCl6 as a host, band gap and optical properties of Cs2AgBiCl6 have been modulated by alloying with M(I), M(II), and M(III) cations at Ag-/Bi-sites. Here, we have employed density functional theory (DFT) with suitable exchange-correlation functionals in light of spin–orbit coupling (SOC) to determine the stability, band gap and optical properties of different compositions, that are obtained on Ag–Cl and Bi–Cl sublattices mixing. On analyzing 64 combinations within Cs2AgBiCl6, we have identified 19 promising configurations having band gap sensitive to solar cell applications. The most suitable configurations with Ge(II) and Sn(II) substitutions have spectroscopic limited maximum efficiency (SLME) of 32.08% and 30.91%, respectively, which are apt for solar cell absorber.

Facile one pot in situ synthesis of ZnS–ZnIn2S4 composite for improved photocatalytic applications

Present work utilizes solar-driven photocatalysis as an eco-friendly, green technology to degrade organic contaminants in water. In situ synthesis of ZnS–ZnIn2S4 composite was carried out with one pot facile hydrothermal route. The as prepared composite was characterized with X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Diffuse Reflectance Spectroscopy (DRS). The composite was found to have an effective optical bandgap of 2.82 eV explicating its activity in the visible region of solar spectrum. Photoactivity of the composite was utilized for degradation of organic contaminants (e.g. Methylene Blue, Ciprofloxacin) in water under UV, visible light and direct sunlight irradiation. The efficiency of the catalyst and kinetics of degradation are discussed in detail. The composite also shows an improved photocurrent density of 1.14 μA/cm2 and a photocatalytic degradation rate constant of 0.041 min−1. This work provides an insight to the development of a novel in situ composite with enhanced photocurrent generation and improved photocatalytic activity that can be utilized for environmental remediation applications.

Structural, electronic, optical, thermoelectric and photocatalytic properties of SiS/MXenes van der Waals heterostructures

Vertical stacking of two-dimensional materials into layered van der Waals heterostructures are recently considered as promising candidates for optoelectronic devices because they can combine advantages of the individual 2D materials. MXenes have emerged an appealing optoelectronic material due to the desirable electronic properties. This paper focuses on the structural, electronic, optical, thermoelectric and photocatalytic properties of SiS, Ti2CO2, Zr2CO2, Hf2CO2 monolayers and their corresponding van der Waals (vdW) heterostructures. These materials and their heterostructures are dynamically stable. All unstrained heterostructures show indirect band gap semiconductors except SiS-Ti2CO2 which exhibits metallic nature. The higher carrier mobility of the metallic, SiS-Ti2CO2 is followed by its least effective mass. The induction of considerable biaxial (compressive and tensile) strain offers metallic characteristics to SiS-Ti2CO2 and SiS-Zr2CO2 while SiS-Hf2CO2 retains its semiconducting nature. SiS-Zr2CO2/SiS- Hf2CO2 show type-I/type-II band alignment which are highly suitable for electronic, optical, nanoelectronic and optoelectronic devices. Additionally, the least effective mass of SiS-Zr2CO2 offers higher carrier mobility. Bader charge analysis revealed that MXenes dissipate the charge carriers to SiS monolayer. Furthermore, a good comparison of thermoelectric performance of all the systems illustrates their significant power factor that is well interpreted at 300 K and 800 K. Several excitonic peaks are observed of the systems in the visible region of solar spectrum. Furthermore, valence (conduction) band edge potentials are calculated to understand the photocatalytic behavior of these systems.

Cuprous oxide film sputtered on monolayer graphene for visible light sensitive heterogeneous photocatalysis

A two dimensional thin film catalyst system was produced in this study as Cu2O/2D graphene on the copper foil having catalytic activity in the visible region of solar spectrum. Catalyst structure was characterized by scanning electron microscopy, energy dispersive x-ray spectroscopy, x-ray diffraction, atomic force microscopy, UV–visible diffuse reflectance spectroscopy and confocal Raman spectroscopy techniques. Existence of photocatalytic activity was demonstrated by hydrogen peroxide degradation under 14 W LED light. Using monolayer graphene in the design of the catalyst increased the activity almost 16 times compared to the neat catalyst without graphene. Activity in the light was 8.6 times higher than the dark. Graphene used in the catalyst system was perfect monolayer having no defect and its 2D/G ratio was 2.72. Surface roughness of the catalyst according to the atomic force microscopy results was found to be 1.1 µm. Surface morphology of thin film catalyst was channeled like, mostly dimpled but had no apparent micro cracks with a thickness value of 290.9 nm ± 10 nm.

Molecular design of porphyrin dyes using different electron-withdrawing moieties for high performance dye-sensitized solar cells

In spite of having some favorable light harvesting properties, porphyrins are still inferior to ruthenium dyes in dye sensitized solar cells. Nevertheless, there are enormous scope for improving the efficacy of these dyes. To recognize the connection between the structure and light-harvesting properties, herein, we have made a systematic theoretical investigation on a series of Zn-porphyrin dyes. We have explored the effect of benzodithiazole based model acceptor groups on their photovoltaic properties, especially on the electron injection dynamics with TiO2 photoanode. The model dyes show enhance light absorption in the entire visible region of solar spectrum in comparison to the parent dye which has been synthesized recently. The interfacial electron transfer (IET) dynamics reveals that suitable heteroatom substitution in acceptor group offers faster (sub-picosecond) electron injection as compared to the parent dye.

Synthesis and characterization of inorganic K3Bi2I9 perovskite thin films for lead-free solution processed solar cells

Bismuth halide perovskites have been proposed as a non-toxic and chemically stable alternative to lead halide perovskites. Despite being highly stable, the devices based on bismuth perovskites have not been able to compete with the lead counterparts in terms of its efficiencies. The compounds that have been extensively studied i.e. Cs3Bi2I9 and MA3Bi2I9 form 0D (dimer) structures that possess wide indirect band gaps and poor charge transport properties which hinders the performance of devices based on these materials. Theoretical studies have revealed that replacing bigger A cation like Cs/MA by smaller cation like potassium (K) could favor the formation of layered 2D structures rather than 0D structure. We have synthesized inorganic K3Bi2I9 perovskite thin films by facile one-step spin coating method and investigated its structural, optical and morphological properties. The fabricated films showed strong absorption in UV and visible region of solar spectrum and possess optical band gap ∼2 eV. On comparison with the Cs analogue, it is observed that reduction in the cation size (Cs to K) hardly changes the band gap of K3Bi2I9 films which implies that the band gap of A3Bi2I9 perovskite is insensitive to A-site variation. Films deposited on preheated substrates showed comparatively good coverage without voids on the film surface. Our preliminary studies on this material showed that the films deposited by one-step solution method favored 0D structure rather than the expected 2D layered structure.

Enhanced Light Absorption and Charge Carrier Management in Core‐Shell Fe2O3@Nickel Nanocone Photoanodes for Photoelectrochemical Water Splitting

AbstractSolar driven photoelectrochemical (PEC) water splitting is a clean and sustainable approach to generate green fuel, Hydrogen. Hematite (Fe2O3) is considered as potential photoanode because of its abundance, chemical stability and suitable band gap, though its short carrier diffusion length puts a limit on the film thickness and subsequent light absorption capability. In this regard, here we have designed and constructed a unique photoanode by depositing ultrathin films of Fe2O3 on purpose‐built three‐dimensional (3D) nickel nanocone arrays. In this design, 3D nanostructures not only provide ameliorated surface area for PEC reactions but also enhance light absorption capability in ultrathin Fe2O3 films, while ultrathin films promote charge carrier separation and effective transfer to the electrolyte. The 3D electrodes exhibit a substantial improvement in light absorption capability within the entire visible region of solar spectrum, as well as enhanced photocurrent density as compared to the planar Fe2O3 photoelectrode. Detailed investigation of reaction kinetics suggests an optimum Fe2O3 film thickness on 3D nanocone arrays obtained after 6 deposition cycles in achieving maximum charge carrier separation and transfer efficiencies (82 % and 88 %, respectively), mainly ascribable to the increased charge carrier lifetime overcoming recombination losses.

Recent Progress and Emerging Applications of Rare Earth Doped Phosphor Materials for Dye‐Sensitized and Perovskite Solar Cells: A Review

Although the efficiency of Dye-sensitized and Perovskite solar cell is still below the performance level of market dominance silicon solar cells, in last few years they have grabbed significant attention because of their fabrication ease using low-cost materials, and henceforth these cells are considered as a promising alternative to commercial photovoltaic devices. However, third generation solar cells have significant absorption in the visible region of solar spectrum, which confines their power conversion efficiency. Subsequently, the performance of current photovoltaics is significantly hampered by the transmission loss of sub-band-gap photons. To overcome these issues, rare earth doped luminescent materials is the favorable route followed to convert these transmitted sub-band-gap photons into above-band-gap light, where solar cells typically have significant light-scattering effects. Moreover, the rare earth based down/up conversion material facilitates the improvement in sensitization, light-scattering and device stability of these devices. This review provides insight into the application of various down/up conversion materials for Dye-sensitized and perovskite solar cell applications. Additionally, the paper discusses the techniques to improve the photovoltaic performance in terms of current density and photo voltage in detail.

Efficiency of Solar Cells Based on Natural Dyes with Plasmonic Nanoparticle-Based Photo Anode

Cheap and efficient dye sensitized solar cells (DSSCs) can be prepared using natural dyes responding in the visible region of solar spectrum. Localized surface plasmon resonance (LSPR) plays a very important role for the improvement in the efficiency of DSSCs by using Plasmonic nanoparticles (PNPs) for exploiting the visible portion of the solar radiation by transferring the energy from dye to PNP. This energy transfers from dye to semiconductor TiO2 through PNP which increases the overall photo catalytic activity. In the present study, Al-doped TiO2 photoanodes were prepared via sol–gel route and used for DSSC application. Various natural and synthetic dyes are prepared and the optical transmittance and absorbance of the dyes are measured in the wavelength range of 250–850[Formula: see text]nm using UV-Vis spectroscopy and they are used in DSSC. Natural dyes extracted from fruits and synthetic dye based on Ruthenium (Ru) metal complex is used as sensitizers. Power conversion efficiency (PCE) of solar cells utilizing different dyes is compared. Out of the various natural dyes, beetroot and strawberry extracts based dyes show good absorbance in the visible range of electromagnetic spectrum. On the other hand, synthetic dyes based on Ru complex show strong absorbance over a wide range of visible spectrum. The absorbance increases with increase in concentration of Ru in ethanol. The extracts of beetroot, strawberry and mixed fruits show a peak in absorbance spectra at 501nm, 416nm and 332nm, respectively, indicating the absorption over a wide range of visible spectrum. Maximum efficiency of DSSCs utilizing PNPs sensitized with beetroot and strawberry dyes are found to be 1.5% and 1.3%, respectively.

Solar Decolorization of Methylene Blue by Magnetic MgFe2O4-MWCNT/Ag3VO4 Visible Active Photocatalyst

MgFe2O4-MWCNT/Ag3VO4 photocatalyst was prepared for benefiting the visible region of solar spectrum. Prepared catalyst was characterized by using scanning electron microscope (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDX). Photocatalytic activity was measured by methylene blue (MB) decolorization under visible light obtained from a 105-W tungsten light bulb. Dye decolorization and its kinetics were followed up by means of a UV-vis spectrophotometer. Kinetic model of decolorization was found to be compatible with first-order kinetics. The effects of pH and concentration of MB solution on the decolorization efficiency were determined. Low and high pH conditions were found to be more effective in increasing the MB decolorization yield and rate. On the other hand, due to the low transparency of concentrated MB solutions, an increase on decolorization time and a lowering in decolorization yield were encountered. Thanks to the magnetic MgFe2O3 nanoparticles, 96% of the catalyst could be recovered by a simple magnetic bar. It was observed that simulated wastewater containing MB was also successfully decolorized showing that visible region-sensitive MgFe2O4-MWCNT/Ag3VO4 photocatalyst can be benefited as a potential, efficient, and reusable material for the removal organic pollutants in aquatic environment.

Comparative study of absorption band edge tailoring by cationic and anionic doping in TiO2

Abstract Titanium dioxide (TiO2) is one of the most favored metal oxide semiconductors for the use as photoanode in photoelectrochemical cells (PEC) splitting the water into hydrogen and oxygen. However, the major impediment is its large bandgap that limits its utilization as photoanode. Doping has evolved as an effective strategy for tailoring optical and electronic properties of TiO2. This paper describes the synthesis of undoped as well as iron (Fe, cationic) and nitrogen (N, anionic) doped nanocrystalline titanium dioxide by sol-gel spin coating method for solar energy absorption in the visible region. All the prepared thin films were characterized by X-ray diffraction and UV-Vis spectroscopy. Doping of both Fe and N into TiO2 resulted in a shift of absorption band edge towards the visible region of solar spectrum.

A Facile Synthesis of Copper Oxide Nanorods for Photocatalytic Degradation of Organic Pollutant and Inactivation of Pathogens

In the recent years, green synthesis of nanomaterials has received a great attention to researchers in worldwide due to eco-friendly and scalable synthesis. Here, we report a green synthesis of copper oxide (CuO) nanorods via sonochemical assisted approach. The crystalline structure, band gap and morphology of as prepared CuO nanorods were investigated by UV-Vis diffuse reflectance (UV-Vis/DRS), Fourier Transform infrared spectroscopy, powder X-Ray diffraction (XRD) pattern and scanning electron microscopy (FESEM-EDX). The bandgap of as prepared CuO nanorods was found to be 2.0 eV, which is fall in the visible region of solar spectrum. FTIR demonstrated that there is strong interaction between Cu and oxygen in prepared CuO. XRD results reveal the formation of phase pure and crystalline CuO. FESEM images clearly show the rod like morphology of CuO and the presence of elemental copper and oxygen in EDX, confirms the formation of CuO. The photocatalytic degradation activity of CuO nanorods was examined against a model dye pollutant, nitrobenzene (NB) under visible light irradiation. CuO nanorods were effectively degraded the NB under visible light irradiation. CuO nanorods acts as potent and shows enhanced antimicrobial agent against pathogenic fungi, Candida albicans and bacteria, Escherichia coli.

Ab-initio study of thermodynamic stability, thermoelectric and optical properties of perovskites ATiO3 (A=Pb, Sn)

The physical behavior of perovskites ATiO3 (A=Pb, Sn) has been explored by using density functional theory based full-potential linearized-augmented-plane-wave plus local-orbital (FP-LAPW+lo) method. The lattice parameters calculated from the optimized structures by using Murnaghan equation of state and Chapin's method have been found in good agreement with the available literature that ensures the reliability of the adopted methodology. Moreover, the optoelectronic and thermoelectric properties have been elaborated by using modified Becke-Johnson exchange potential. The optical behavior has been explored in terms the dielectric constants, refractive indices, absorption spectra and optical loss factors. The absorption spectra of these materials reveal a large absorption in the visible and low ultraviolet part of incident light. The thermoelectric properties of ATiO3 are explained in terms of electrical conductivities, thermal conductivities, power factors, and the specific heat capacities. The ATiO3family of pervoskites has been found to exhibit the bandgaps falling in the visible region of solar spectrum and show high values of thermal efficiency that make them potential multifunctional candidates for optoelectronic and energy harvesting applications.

Photocatalytic treatment of dye wastewater and parametric study using a novel Z-scheme Ag2CO3/SiC photocatalyst under natural sunlight

Ag2CO3 is a known photocatalyst active in the visible region of solar spectrum. In the present study, a series of novel hybrid Ag2CO3/SiC nanostructures have been successfully synthesised through a simple precipitation route. The photocatalytic performance was evaluated by the degradation of MB under natural solar irradiation. It was observed that heterojunction with SiC improves its photoactivity by inducing a charge transfer between SiC and Ag2CO3 mimicking the Z-scheme in photosynthesis, proved by scavenger studies. The photocatalysts were characterized by XRD, SEM with EDX, TEM, TGA-DTG and UV-Vis/NIR. The best photocatalytic results and formal quantum efficiency (FQE) under natural sunlight were obtained with SCSC-12 nano-composite. The percentage photo-discolouration of MB over SCSC-12 was 98% against 90% with conventional TiO2. Factors viz., photocatalyst dosage, solution pH, solar intensity, substrate and its initial concentration and speed of agitation were found to influence photo-treatment. Corresponding optimum parametric values have been found and reported in terms of FQE. As a case study, performance of the photocatalyst was investigated on a real industrial effluent and rate expression developed in terms of TOC and [TOC]0. The present work, which includes a parametric study, has been carried out in direct solar light and is expected to be useful in real-time solar photocatalytic design of reactors and other solar applications for environmental remediation.