Solar Energy Harvesting Applications Research Articles

Tea stain-inspired solar energy harvesting polyphenolic nanocoatings with tunable absorption spectra

Discovery and development of new sustainable photothermal materials with tunable light absorption spectra play a key role in solar energy harvesting and conversion. One possible solution to this quest is to check nature as a source of matters or inspiration. Inspired by the formation of tea stains, a unique class of dark stain materials generated by the interfacial reaction between tea polyphenols and metal substance, we reported the facile preparation and screening of a series of photothermal nanocoating layers via the metal ion (i.e. Cu(II),Fe(III), Ni(II), Zn(II)) promoted in situ polymerization of typical phenolic moieties of tea polyphenols (i.e., catechol and pyrogallol). It was found that those resulting metal-polyphenolic nanocoatings showed various promising features, such as high blackness and strong adhesion, excellent and tunable light absorption properties, good hydrophilicity and long-term stability. We further fabricated the photothermal composite devices by in situ formation of metal-polyphenolic nanocoatings on pristine silks for solar desalination, which demonstrated promising durable evaporation behaviors with excellent evaporation rates and steam generation efficiencies. We believe that this work could provide more opportunities towards new types of bio-inspired and sustainable photothermal nanomaterials for solar energy harvesting applications such as water desalination.

Nonmetallic Broadband Visible-Light Absorbers With Polarization and Incident Angle Insensitivity

We have proposed and theoretically analyzed nonmetallic broadband visible-light absorbers based on alternating SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /InAs thin films on SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> substrate. Compared with the conventional absorbers, the proposed SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /InAs structure can achieve excellent absorption within a smaller volume. The average absorption can exceed 97% in the wavelength range of 300-850 nm. With a two-dimensional InAs grating atop, the device can achieve the average absorption of >92% with insensitivity to light polarization and incident angles. Due to the advantages of broadband and near-unity absorption, polarization and incident angle insensitivity, controllable and mature fabrication processes, the proposed visible-light absorbers will find wide applications in solar energy harvesting, thermal emission, and water splitting.

Vat Dye Safranin O- and Perylene-Based Conjugated Donor–Acceptor Polyimide as Sensitizer for Dye-Sensitized Solar Cells

Nanocrystalline TiO2 and conjugated polyimide are good composite materials for solar energy harvesting applications. Vat dyes have a specific high color fastness property with high wavelength absorption. By applying this property of vat dyes, we synthesized Safranin O and a perylene 3,4,9,10-tetracarboxylic dianhydride (PTCDA) based conjugated polyimide through the condensation polymerization technique. Synthesized polyimide was used to construct a TiO2–polymer composite material for dye-sensitized solar cells (DSSCs). The synthesized polyimide has good absorption properties, and a small bandgap of 2.23 eV, contains alternating electronaccepting–electrondonating units, and revealed high thermal stability. It shows good electrical properties, i.e., conductivity of the order of ∼10–4 S cm–1 and an activation energy of 0.1 eV before transition and 0.6 eV after transition, follows an Arrheniustype behavior, and has thermal transitions. Fabrication of electrodes and DSSC was performed for determining the photovoltaic properties of the synthesized polyimide. The obtained photovoltaic parameters, i.e., Jsc = 65 μAcm–2, Voc = 0.128 V, and FF = 0.36, demonstrated their successful use in dye-sensitized solar cells.

Two-dimensional ultrathin van der Waals heterostructures of indium selenide and boron monophosphide for superfast nanoelectronics, excitonic solar cells, and digital data storage devices

Semiconducting indium selenide (InSe) monolayers have drawn a great deal of attention among all the chalcogenide two-dimensional materials on account of their high electron mobility; however, they suffer from low hole mobility. This inherent limitation of an InSe monolayer can be overcome by stacking it on top of a boron phosphide (BP) monolayer, where the complementary properties of BP can bring additional benefits. The electronic, optical, and external perturbation-dependent electronic properties of InSe/BP hetero-bilayers have been systematically investigated within density functional theory in anticipation of its cutting-edge applications. The InSe/BP heterostructure has been found to be an indirect semiconductor with an intrinsic type-II band alignment where the conduction band minimum (CBM) and valence band maximum (VBM) are contributed by the InSe and BP monolayers, respectively. Thus, the charge carrier mobility in the heterostructure, which is mainly derived from the BP monolayer, reaches as high as 12 × 103 cm2 V−1 s−1, which is very much desired in superfast nanoelectronics. The suitable bandgap accompanied by a very low conduction band offset between the donor and acceptor along with robust charge carrier mobility, and the mechanical and dynamical stability of the heterostructure attests its high potential for applications in solar energy harvesting and nanoelectronics. The solar to electrical power conversion efficiency (20.6%) predicted in this work surpasses the efficiencies reported for InSe based heterostructures, thereby demonstrating its superiority in solar energy harvesting. Moreover, the heterostructure transits from the semiconducting state (the OFF state) to the metallic state (the ON state) by the application of a small electric field (∼0.15 V Å−1) which is brought about by the actual movement of the bands rather than via the nearly empty free electron gas (NFEG) feature. This thereby testifies to its potential for applications in digital data storage. Moreover, the heterostructure shows strong absorbance over a wide spectrum ranging from UV to the visible light of solar radiation, which will be of great utility in UV—visible light photodetectors.

Rational Design of Azothiophenes-Substitution Effects on the Switching Properties.

A series of substituted azothiophenes was prepared and investigated toward their isomerization behavior. Compared to azobenzene (AB), the presented compounds showed red‐shifted absorption and almost quantitative photoisomerization to their (Z) states. Furthermore, it was found that electron‐withdrawing substitution on the phenyl moiety increases, while electron‐donating substitution decreases the thermal half‐lives of the (Z)‐isomers due to higher or lower stabilization by a lone pair–π interaction. Additionally, computational analysis of the isomerization revealed that a pure singlet state transition state is unlikely in azothiophenes. A pathway via intersystem crossing to a triplet energy surface of lower energy than the singlet surface provided a better fit with experimental data of the (Z)→(E) isomerization. The insights gained in this study provide the necessary guidelines to design effective thiophenylazo‐photoswitches for applications in photopharmacology, material sciences, or solar energy harvesting applications.

Band gap engineering and enhancement of electrical conductivity in hydrothermally synthesized CeO2 ̶ PbS nanocomposites for solar cell applications

The wide band gap of CeO2 limits its application in solar energy harvesting, notwithstanding the exceptional optical and electrical properties due to the presence of unfilled 4f orbitals. Therefore, we combine a narrow band gap semiconductor PbS with CeO2 for band gap narrowing and to achieve enhanced electrical conductivity in the nanocomposites. CeO2 ̶ PbS nanocomposites were synthesized from a combination of as-prepared CeO2 powder and precursors of lead and sulphur using a two-step hydrothermal reaction process. The morphologies and structures of various nanocomposites synthesized at different concentrations of Pb precursor were studied by Field Emission Scanning Electron Microscopy and X-ray diffraction. The average crystallite sizes of the nanoparticles were estimated from XRD analysis and found to be in the range of 11 ̶ 15 nm for all the CeO2 ̶ PbS nanocomposites. The homogeneity and chemical composition were investigated by Energy Dispersed X-ray Analysis and X-ray photoelectron spectroscopy. Similarly, the microstructure study and lattice imaging were carried out with the help of high-resolution transmission electron microscopy. The lattice structure was corroborated by lattice vibration properties studied by micro-Raman spectroscopy. The surface structure and composition, such as the identification of surface functional group and adsorbed species were ascertained with the help of Fourier Transform Infrared Spectroscopy. The optical properties of the CeO2 ̶ PbS were studied by UV–Vis Diffuse Reflectance Spectroscopy. The optical band gaps of the nanocomposites were estimated to be 2.76 ̶ 2.98 eV. The electrical property of the CeO2 ̶ PbS powder was analyzed by recording the current-voltage characteristics of a series of hydraulic pressed pellets. The electrical conductivity obtained for CeO2 ̶ PbS nanocomposites was found to be much higher than that of pristine CeO2 nanoparticles. Hence, the enhanced electrical property with reduced band gap of CeO2 ̶ PbS nanocomposites makes it suitable for optoelectronic devices and solar cell applications.

Vertical graphene nano-antennas for solar-to-hydrogen energy conversion

Effective separation and transfer of photogenerated charge carriers are common issues in solar energy conversion. Strong localized electric fields near functional nanostructures reduce charge recombination and boost energy efficiency and photocatalytic activity. However, common metal-based photocatalytic systems on conducting supports under-utilize infrared (IR) light energy, and suffer from unsatisfactory interface quality and stability, as well as high complexity and cost. Here we develop a photocatalytic nano-antennas simultaneously featuring localized field-enhancement in IR, high electric conductivity, and interface stability. In the nano-antennas, plasma-made all-carbon vertical graphene nanopetals (GPs) are covalently interfaced with high-performance metal-free semiconducting graphitic carbon nitride (g-C3N4) photocatalyst. The photo-induced force microscopy is used to obtain real-space images of localized electric field enhancement in the near-IR and mid-IR ranges along the vertically standing ultra-sharp GP edge nano-antennas. The photocurrent, electrochemical impedance spectra, and time-resolved photoluminescence spectra confirm that the GP edge nano-antennas significantly enhance the photogenerated charge carrier separation, accelerate carrier migration, and prolong carrier lifetime. We also demonstrate the scalability of production of the petal edge nano-antennas. The unique graphene nanoarchitecture offer exotic spectral properties, which are essential for many large-scale solar energy harvesting applications such as photocatalysis, photovoltaics, and solar-thermal water desalination and purification.

A nanofluids and nanocoatings used for solar energy harvesting and heat transfer applications: A retrospective review analysis

It is known that harvesting the solar power is key issue in current scenario because of scarcity of non-renewable energy in future days to come. Hence the solar harvesting systems takes an important stand globally. Grabbing the solar energy is difficult task due to low thermal conductivity of fluids which are carrying heat and poor optical coatings of solar power devices. In order to enhance the heat transfer rate of fluids there should be an alternative, such alternative is nanofluid. Nanofluids are having nanoparticles suspended in base fluids stably. This paper critically reviewed and conveyed the up to date literature of usage of nanofluids and nanocoating’s in solar energy harvesting operating in low, medium and high temperature ranges for effectiveness in performance. Further solar energy conversion systems efficiencies can be raised by using the additives in base fluids termed as nanofluids and nano selective coatings for solar concentrators to improve optical performance.

Recent progress on nanostructure-based broadband absorbers and their solar energy thermal utilization

Nanostructure-based broadband absorbers are prominently attractive in various research fields such as nanomaterials, nanofabrication, nanophotonics and energy utilization. A highly efficient light absorption in wider wavelength ranges makes such absorbers useful in many solar energy harvesting applications. In this review, we present recent advances of broadband absorbers which absorb light by nanostructures. We start from the mechanism and design strategies of broadband absorbers based on different materials such as carbon-based, plasmonic or dielectric materials and then reviewed recent progress of solar energy thermal utilization dependent on the superior photo-heat conversion capacity of broadband absorbers which may significantly influence the future development of solar energy utilization, seawater purification and photoelectronic device design.

Metal Insulator Metal Diode: A Potential Candidate for Energy Harvesting Applications.

Metal-Insulator-Metal (MIM) diodes used for infrared detection and frequency mixing since many decades and their development for energy harvesting applications in rectenna solar cell has accelerated a decade ago. In the horizon of these applications less complex fabrication methodology, accurate simulation methods and optimum material combination are required. Ultra-fast response of MIM diodes makes them a potential candidate for solar energy harvesting applications. Here in this work, the design and fabrication issues of MIM diode from simulation methodology based on insulating thickness properties to the fabrication methodology are discussed. MIM diode for Al-Al₂O₃-Ag combination is fabricated and characteristics such as I(V), asymmetry and non-linearity are reported.

Ultra-broadband and wide-angle perfect solar absorber based on TiN nanodisk and Ti thin film structure

At present, solar energy is widely used as a kind of clean energy. The main solar radiation range under AM 1.5 is about 300 ~ 3000 nm. In this paper, we designed an efficient, ultra-broadband perfect solar absorber to have as long absorption bands in this range as possible to help alleviate the energy problem. The simulation calculations and experiments of the solar absorber show that the absorption bandwidth with absorption greater than 90% is greater than 2100 nm. It is worth noting that the perfect absorption bandwidth with absorption greater than 99% has more than 1600 nm. The absorption rate over the whole wavelength range (300 nm–3000 nm) (weighted directly around the sun by solar AM 1.5) is more than 90%. We can effectively control the absorption spectrum by adjusting the structural parameters. In addition, the proposed solar absorber is polarization independent, both the transverse electrical (TE) mode and the transverse magnetic (TM) mode, Absorption remains above 80% when the wide incidence angle is as high as 50°. Our propose design has high broadband absorption and great potential for solar thermal energy harvesting, thermoelectrics, and thermal emitters applications.

Mimicking flower petals to fabricate self-cleaning and antireflective polymer surfaces

This work explored a facile way to fabricate superhydrophobic and antireflective polymer surfaces using Canna indica flower petals. A simple, inexpensive two-step soft-lithography technique was employed to replicate the surface structures of C. indica flower petals onto two different polymer surfaces namely, polydimethylsiloxane (PDMS) — a hydrophobic polymer and resorcinol–formaldehyde (RF) xerogel — a hydrophilic polymer. First, a negative replica was prepared in PDMS using the flower petal as a template. Second, the negative PDMS replica was later used as a stamp to prepare a positive replica in both PDMS and RF xerogel. These replicated structured surfaces greatly influenced the wettability properties. The contact angle of the replicated PDMS surfaces increased to the nearly superhydrophobic values of 145° (negative PDMS replica) and 144° (positive PDMS replica) compared with that of the plain surface, which is 101°. Interestingly, the contact angle of the replicated RF surface significantly increased to 151° (superhydrophobic) compared with that of the planar RF surface, which is hydrophilic (68°). Furthermore, the replicated polymer surfaces exhibited not only excellent superhydrophobic properties but also antireflective properties. These multifunctional surfaces with superhydrophobicity as well as an omnidirectional antireflective property may find a wide range of applications, such as solar energy harvesting, optical displays and marine applications.

The optimal transmission and dual resonant for different geometrical U-shaped THz nano antenna with surface plasmons (SPs) biosensors

&lt;p&gt;In this study, we focus on plasmonic nanoantenna structures for the U shaped. We will do our simulations with FDTD method (finite difference time domain) by considering commercial software Lumerical. We use U-shaped and play with the geometrical parameters such as length (L), width (W), high (H), to enhance the transmission of light. In addition to this, we will consider the different methods and substrates. U-shaped designed structure by using gold and&lt;strong&gt; &lt;/strong&gt;MgF2 materials and studied how to enhance nanoantenna coefficients to get the highest electric field improvement factor and support multi-spectral resonances, that can be tuned from visible to near-IR wavelengths. For the optimum coefficients, the proposed U-shaped nanoantenna reached the optimal transmission and multi-resonant for different geometrical size. In results shows that in this model are wideband range of wavelengths and optimal transmission and all physical boundary conditions are chosen as perfectly matched layer (PML) to avoid undesired reflections, when we change the size of U-shaped with different materials is used and gets more proposes in the biosensors, biomedical and laser optical communication and for nanoantennas can also be deposited on layered substrates to enable solar cells and energy harvesting applications .And we can see that there are two resonances at (𝝺&lt;sub&gt;1 &lt;/sub&gt;and 𝝺&lt;sub&gt;2&lt;/sub&gt;) wavelength range (500-950) nm, the first one has a transmission 0.73 at wavelength 700nm; and the other one has a transmission 0.88 at wavelength 845nm from this designed. We will investigate the structure of nanoantenna to be used as biosensors.&lt;/p&gt;&lt;p&gt; &lt;/p&gt;

Design of new imidazole-derivative dye having donor-Π-acceptor moieties for highly efficient organic-dye-sensitized solar cells

In the present work, we have synthesised donors/acceptor substituted derivative of imidazole 4-(1-(3-chloro-4-nitrophenyl)-4,5-diphenyl-1H-imidazol-2-yl)benzoic acid (CNI) via one-pot synthetic method and has been characterized by spectroscopic methods such as 1H-NMR, IR, SEM and EDX. The photophysical properties like, solvatochromic shift and quantum yield were estimated. Energy band gap of the CNI dye was calculated in various solvents using theoretical and experimental methods. Further, photosensitization of TiO2 nanoparticles from CNI dye has been investigated using absorption, steady state and time resolved fluorescence methods. The increase in absorbance and decrease in fluorescence spectra with different concentrations of TiO2 nanoparticles confirmed the possibility of interactions between dye and TiO2 nanoparticles. Rehm-Weller relation suggests that, decrease in fluorescence of CNI dye was due to photo-induced electron transfer process and the Stern-Volmer studies suggest that, the fluorescence quenching mechanism was due to combined dynamic and static quenching process. The photo-induced electron transfer process has been used in solar energy harvesting applications by fabricating CNI dye sensitized solar cell. Photovoltaic energy conversion efficiency and fill factor of the CNI dye were found to be 1.85 % and 0.57 respectively.

A 2.4 GHz Rectenna Based on a Solar Cell Antenna Array

Combined solar and radio frequency (RF) harvesting systems are drawing attention by offering self-powered ability to low-power devices, an essential aspect to the success of the Internet of Things. One of the main challenges of these harvesting systems is to improve rectennas efficiency by optimizing the individual energy collection and conversion capacity of each source. To overcome this issue, this letter presents a novel 2.4-GHz rectenna structure for solar and radio frequency energy harvesting applications based on a coplanar antenna array integrated with multicrystalline solar cells, whose aluminum rear terminals are used as radiators for the antenna array. The results obtained by simulations and measurements show that it is possible to collect energy from two different types of sources in a complementary manner, using the rectenna design proposed, making it possible to feed low-power devices remotely.

UV-assisted water splitting of stable Cl-doped ZnO nanorod photoanodes grown via facile sol-gel hydrothermal technique for enhanced solar energy harvesting applications

Vertically aligned pristine ZnO and Cl-doped ZnO nanorod arrays were grown by a simple, cost-effective sol-gel and hydrothermal method. These nanorods (NRs) were fabricated to demonstrate their potential as highly efficient photoelectrodes to be used in photoelectrochemical water splitting applications. XRD measurements indicate that all the fabricated NRs have preferably grown along c-axis (0 0 2) direction. FESEM images confirmed hexagonal shaped NRs grown along (0 0 2) direction. The light harvesting efficiency of pristine ZnO NRs was enhanced with increase in doping concentration which is due to rise in absorbance as verified by UV–Vis absorption spectroscopy. When used as photoanodes in PEC water splitting under UV illumination, these NR arrays exhibits an enhanced photocurrent density of 2.16 mA cm−2 at 1.2 V vs. Ag/AgCl which is much higher than undoped ZnO NRs (0.103 mA cm−2). Cl_Z3 photoanode exhibits a stable photocurrent density even after continuous illumination of 12 h. The significantly improved photoresponse behavior and high photostability with suitable bandgap and high light harvesting efficiency of these photoanodes provides valuable platforms for efficient photoelectrochemical water splitting applications.

An On-Glass Optically Transparent Monopole Antenna with Ultrawide Bandwidth for Solar Energy Harvesting

An on-glass optically transparent monopole antenna with ultrawide bandwidth is presented in this work, and the proposed antenna is of ring shape and coplanar waveguide fed structure. Optically transparent indium tin oxide (ITO) thin film with a thickness of ~ 160 nm is used as the conductive layer, which is sputtered on an optically transparent glass substrate. An impedance bandwidth of 6 GHz from 1 to 7 GHz is achieved, with a return loss lower than −10 dB, meaning a fractional bandwidth of 150%. The proposed antenna exhibits reasonable radiations of omni-directionality in the H plane and bi-directionality in the E plane. Like other transparent antennas discussed in literature, the antenna gain is relatively low (−4 dBi at 5 GHz). In order to optimize the antenna performance, multi-film approach is proposed to reduce its sheet resistance, and the result shows that the antenna gain at 4 GHz can be improved from −8 dBi to 5 dBi when optimizing the sheet resistance from 10 Ω / sq to 0.01 Ω / sq . The designed antenna possesses a high optical transparency, which makes it easy to integrate to the surface of windows or display panels, and it can be applied for solar energy harvesting and many other ultra-wideband applications, with little chance of detection.

Electromagnetic Effective Medium Modelling of Composites with Metal-Semiconductor Core-Shell Type Inclusions

The possibility of using light to drive chemical reactions has highlighted the role of photocatalysis as a key tool to address the environmental and energy issues faced by today’s society. Plasmonic photocatalysis, proposed to circumvent some of the problems of conventional semiconductor catalysis, uses hetero-nanostructures composed by plasmonic metals and semiconductors as catalysts. Metal-semiconductor core-shell nanoparticles present advantages (i.e., protecting the metal and enlarging the active sites) with respect to other hetero-nanostructures proposed for plasmonic photocatalysis applications. In order to maximize light absorption in the catalyst, it is critical to accurately model the reflectance/absorptance/transmittance of composites and colloids with metal-semiconductor core-shell nanoparticle inclusions. Here, we present a new method for calculating the effective dielectric function of metal-semiconductor core-shell nanoparticles and its comparison with existing theories showing clear advantages. Particularly, this new method has shown the best performance in the prediction of the spectral position of the localized plasmonic resonances, a key parameter in the design of efficient photocatalysts. This new approach can be considered as a useful tool for designing coated particles with desired plasmonic properties and engineering the effective permittivity of composites with core-shell type inclusions which are used in photocatalysis and solar energy harvesting applications.

Solar thermal absorber based on dielectric filled two-dimensional nickel grating

In this paper, a solar thermal absorber based on a dielectric filled two-dimensional nickel grating is designed and numerically investigated for wide-angle and polarization-independent broadband absorption. The absorption of the proposed two-dimensional meta-surface absorber reaches nearly 100% in the whole visible region (400-800 nm). The physical mechanisms responsible for the high absorption including the impedance matching with the free space, the cavity resonances and the surface plasmonic resonances have been elucidated in detail. The strong resonances effectively trap the incident light in the nano-cavities and then dissipate it by the ohmic losses of the metal, giving rise to the high absorption of the proposed absorber. The meta-surface absorber may find applications in solar cells, photovoltaics, thermos-photovoltaics, thermal emitters, plasmonic sensors, and solar-energy harvesting.

Charge Generation in Monolayer Transition Metal Dichalcogenides

At the monolayer level, many layered 2D transition metal dichalcogenides (TMDCs) are direct bandgap semiconductors in which photo-excitation creates strongly bound excitons. To incorporate these excitonic semiconductors into solar energy harvesting and conversion devices, it is critical to dissociate excitons to produce long-lived free charge carriers. There are still many open questions regarding the fundamental steps of exciton dissociation and subsequent recombination of charge carriers within 2D TMDCs. These include the roles of defects and traps in localizing charges, the types of interfaces that facilitate fast charge separation and slow recombination, and the role of charge diffusion/delocalization in overcoming the Coulomb binding energy following charge separation. In this talk, I will discuss our efforts at answering some of these questions using a number of 2D TMDC model systems and interfaces. We observe long-lived charge generation in certain neat 2D TMDCs that can be related to specific growth-related defects. Charge generation can also be enhanced by creating interfaces with the appropriate energetics for separating electrons and holes, and the lifetime of the charge-separated state is tied to the degree to which the carrier(s) can escape the interface through diffusion and/or delocalization. These studies provide insight into harnessing the potential of monolayer 2D TMDCs in solar energy harvesting and solar fuels applications.