Solar Conversion Research Articles

Interfacial Connections between Organic Perovskite/n+ Silicon/Catalyst that Allow Integration of Solar Cell and Catalyst for Hydrogen Evolution from Water

AbstractThe rapidly increasing solar conversion efficiency (PCE) of hybrid organic–inorganic perovskite (HOIP) thin‐film semiconductors has triggered interest in their use for direct solar‐driven water splitting to produce hydrogen. However, application of these low‐cost, electronic‐structure‐tunable HOIP tandem photoabsorbers has been hindered by the instability of the photovoltaic‐catalyst‐electrolyte (PV+E) interfaces. Here, photolytic water splitting is demonstrated using an integrated configuration consisting of an HOIP/n+silicon single junction photoabsorber and a platinum (Pt) thin film catalyst. An extended electrochemical (EC) lifetime in alkaline media is achieved using titanium nitride on both sides of the Si support to eliminate formation of insulating silicon oxide, and as an effective diffusion barrier to allow high‐temperature annealing of the catalyst/TiO2‐protected‐n+silicon interface necessary to retard electrolytic corrosion. Halide composition is examined in the (FA1‐xCsx)PbI3 system with a bandgap suitable for tandem operation. A fill factor of 72.5% is achieved using a Spiro‐OMeTAD‐hole‐transport‐layer (HTL)‐based HOIP/n+Si solar cell, and a high photocurrent density of −15.9 mA cm−2 (at 0 V vs reversible hydrogen electrode) is attained for the HOIP/n+Si/Pt photocathode in 1 m NaOH under simulated 1‐sun illumination. While this thin‐film design creates stable interfaces, the intrinsic photo‐ and electro‐degradation of the HOIP photoabsorber remains the main obstacle for future HOIP/Si tandem PEC devices.

Enhanced Photothermal Steam Generation and Gold Using the Efficiency of Ultralight Gold Foam with Hierarchical Porosity

Controlling the optical properties of metal plasma nanomaterials through structure manipulation has attracted great attention for solar steam generation. However, realizing broadband solar absorption for high-efficiency vapor generation is still challenging. In this work, a free-standing ultralight gold film/foam with a hierarchical porous microstructure and high porosity is obtained through controllably etching a designed cold-rolled (NiCoFeCr)99Au1 high-entropy precursor alloy with a unique grain texture. During chemical dealloying, the high-entropy precursor went through anisotropic contraction, resulting in a larger surface area compared with that from the Cu99Au1 precursor although the volume shrinkage is similar (over 85%), which is beneficial for the photothermal conversion. The low Au content also results in a special hierarchical lamellar microstructure with both micropores and nanopores within each lamella, which significantly broadens the optical absorption range and makes the optical absorption of the porous film reach 71.1-94.6% between 250 and 2500 nm. In addition, the free-standing nanoporous gold film has excellent hydrophilicity, with the contact angle reaching zero within 2.2 s. Thus, the 28 h dealloyed nanoporous gold film (NPG-28) exhibits a rapid evaporation rate of seawater under 1 kW m-2 light intensity, reaching 1.53 kg m-2 h-1, and the photothermal conversion efficiency reaches 96.28%. This work demonstrates the enhanced noble metal gold using efficiency and solar thermal conversion efficiency by controlled anisotropic shrinkage and forming a hierarchical porous foam.

A portable thermostatic molecular diagnosis device based on high-efficiency photothermal conversion material for rapid field detection of SARS-CoV-2

The outbreak of the novel coronavirus (SARS-CoV-2) has seriously harmed human health and economic development worldwide. Studies have shown that timely diagnosis and isolation are the most effective ways to prevent the spread of the epidemic. However, the current polymerase chain reaction (PCR) based molecular diagnostic platform has the problems of expensive equipment, high operation difficulty, and the need for stable power resources support, so it is difficult to popularize in low-resource areas. This study established a portable (<300 g), low-cost (<$10), and reusable molecular diagnostic device based on solar energy photothermal conversion strategy, which creatively introduces a sunflower-like light tracking system to improve light utilization, making the device suitable for both high and low-light areas. The experimental results show that the device can detect SARS-CoV-2 nucleic acid samples as low as 1 aM within 30 min.

MXene/MnO2 nanocomposite coated superior salt-rejecting biodegradable luffa sponge for efficient solar steam generation

Solar steam generation is widely regarded as one of the potential green approaches for freshwater regeneration by utilizing solar energy. Herein, the MXene/MnO2 nanocomposite-coated biodegradable luffa sponge (Ti3C2-MnO2@LS) is proposed as an efficient solar evaporator for solar steam generation. The thin layer of Ti3C2-MnO2 coated on the surface of the luffa sponge (LS) serves as the solar absorber and enhances the hydrophilicity of the LS, while the thermally insulating LS layer with microporous structure endows sufficient water transportation and localizes heat for interfacial water evaporation. Combining MXene with MnO2 can increase the surface area as well as the stability. The Ti3C2-MnO2@LS delivers a solar evaporation rate as high as 1.36 kg m−2 h−1, with a solar steam conversion efficiency of 85.28 % under one sun irradiation. Furthermore, this Ti3C2-MnO2@LS exhibits superior salt-rejecting properties even under highly concentrated saltwater desalination and excellent wastewater purification performance. This work demonstrates the prospects of combining novel 2D materials with biomass-based materials for practical solar steam generation.

Aggregation Triggers Red/Near-Infrared Light Hydrogen Production of Organic Dyes with High Efficiency

Integrating broad-band red/near-infrared (NIR) light harvesting and efficient charge separation in a semiconductor is a crucial prerequisite for the realization of high photocatalytic efficiency but remains a challenge. Here, we discover that eosin Y (EY) aggregates exhibit strong red/NIR-light harvesting induced by electronic couplings between adjacent EY molecules. Simultaneously, the aggregates are favorable for exciton dissociation and formation of charge-separation states, greatly inhibiting charge recombination. The quantum yield (QY) of EY aggregates for hydrogen production highly reaches 23.6% at 610 nm. More importantly, this general concept of aggregation-induced red/NIR-light photocatalysis was observed in a series of typical organic dyes (11 examples). Impressively, the QY of cobalt phthalocyanin aggregates for hydrogen production is calculated to be 17.2% at 800 nm, which is the highest value among NIR-light-driven H2-evolution systems (≥800 nm) ever reported. This study unlocks a fresh realm of artificial photosynthesis, which uses dye aggregates for red/NIR-light solar conversion.

Design and application of a novel direct light-driven thermogravimetric analyzer

Thermogravimetric analysis is one of the evaluation means widely used to characterize thermoinduced chemical reaction and mass variation processes. However, the emergence of photothermal characteristics research makes traditional thermogravimetric analysis unable to meet the requirements. Therefore, a novel direct light-driven thermogravimetric analyzer is designed for fast photothermal integrated pyrolysis weight loss measurement based on the principle of high temperature measurement under light flux. The photothermal conversion characteristics are studied by analyzing the calcination progress of the blackened calcium carbonate particles. At the same time, the error and uncertainty analysis of the instrument is carried out. Compared with the conventional thermogravimetric electric heating approach, the direct light-driven thermogravimeter provides the same environment as the actual solar photothermal capture and utilization scenarios and enables getting deep insights into the mechanism of the photothermal conversion and chemical reaction kinetics involved which are consistent with the real solar-thermal energy applications. Its unique photothermal integrated design is also valuable for the composition analysis, kinetic analysis or evaluation of solid-gas balance of the materials, which provides an important analysis method for solar photothermal conversion.

Making Eu2+- and Sm2+-Doped Borates Fit for Solar Energy Applications

Despite the development of many luminescent materials for various applications, only a few of these phosphors are applicable for solar energy generation applications. This study used the conventional solid-state reaction method to synthesize different strontium borate compounds codoped with divalent europium and samarium ions. The material was optimized by varying the experimental procedure, the molar ratio of the boron, and the molar ratios of both codopants. Strontium hexaborate doped with a relatively high europium concentration and a low samarium concentration (Sr0.89B6O10:Eu0.1, Sm0.01) gave the optimum optical properties. These properties included a broad excitation range from 220 to 600 nm containing contributions from divalent europium and samarium ions. The material exhibited strong and narrow emission in the region from 650 to 850 nm following radiative transitions within the divalent samarium ions. The internal luminescence quantum efficiency of the optimized material was 79% (λex = 508.5 nm). There was no spectral overlap between the excitation and emission spectra, thereby reducing the reabsorption probability. These marked characteristics make this phosphor material appropriate for use as a solar radiation converter or for use in luminescent solar concentrators.

Influence of Morphology Change on Photoelectrochemical Activity of Cerium Oxide Nanostructures

Aims: Photocatalysis has become a crucial area in the field of energy generation Background: The conversion of solar energy into chemical or thermal energy for various energy related applications has taken precedence over many traditional research areas. Objective: The urgency to become independent of non-renewable energy resources is paramount due to issues of global warming. Objective: The urgency to become independent of non-renewable energy resources is paramount due to issues of global warming. Method: To that end, researchers are exploring various material systems, geometries and material combinations to obtain ideal photocatalysts for efficient solar conversion. Here, the nanostructures were fabricated via electrodeposition. Results and Discussion: The morphology was controlled by varying the concentration of chemical additive, namely dimethyl sulfoxide, during the deposition process. The morphology controlled cerium oxide nanostructures were thoroughly characterized and tested for their photoelectrochemical performances. Conclusion: Our present investigation contributes to this area of research by studying the influence of morphology on the photoelectrochemical activity of cerium oxide nanostructures.

Synthesis and experimental investigations of organic perovskite solar cell material; 2,5-bis(5-aminofuran-2-yl) thiophene 1,1-dioxide; photo-voltaic data validation using computational model and spectroscopic tools

The Doped crystal architectures based on the Perovskite structure are most promising for creating photovoltaic solar cells. In recent years, much research effort has been directed towards increasing the solar power conversion efficiency of organic crystal materials. The ultimate challenge is to improve the light-harvesting power gain in organic synthetic materials and it was proved from the attainment of the Birefringence (Δn) Kλ/t −1.98. In this context, we report herein fabrication of organic 2,5-bis(5-aminofuran-2-yl) thiophene 1,1-dioxide as a perovskite-like lattice in the form of molecular clusters. Its photo-conversion efficiency was calculated as 18%. Its short-circuit current density was determined as JSC = 0.91 mA/cm2, with open-circuit voltage VOC of 1.05 V. The charge transfer (CT) exciton binding energy variation of dielectric constant of the material medium has been calculated. The diffusion path length was defined as <10 Å and the direct band gap was measured as 2.15 eV. The Urbach energy of the prepared sample was estimated as 110–220 meV. The molecular mechanism of exciton productions in the photo-voltaic process has been probed through the use of computational software and experimental tools. The light harvesting ability has been assessed in terms of morphological, optical and electro-optical properties. To characterize weak interactions between the organic molecular sites, vibrational studies have been carried out on polar and nonpolar bonds. The production of Frenkel excitons at the HOMO-LUMO interface and the binding energy variation for electron-hole dissociation has been estimated from the Coulomb capture radius. The photo-energy conversion efficiency and fill factor (FF = 0.511) have been estimated to prove the efficiency of the cell.

Preliminary study on photo-thermal conversion investigation of compound parabolic concentrator for eliminate light escape in vacuum tube interlayer

The ELE-CPC (Eliminate Light Escape Compound Parabolic Concentrator, ELE-CPC) system with vacuum tube absorber is constructed to solve the problem of light escaping in the vacuum interlayer when the conventional vacuum tube absorber is coupled to CPC. The solar ELE-CPC photo-thermal conversion model is established theoretically, and the reliability of the model is validated by outdoor experiments. It is found that the average output temperature of ELE-CPC system is 366.4 K, the average thermal efficiency is 61.3%, and the maximum relative error of the theoretical model is less than 13.2%. The thermal collection efficiency of the ELE-CPC system improves with the increase of its flow rate. Evaluation of the operating characteristics of ELE-CPC showed that the useful energy obtained by ELE-CPC increased throughout the year, especially in April, the average daily utilized solar energy obtained by ELE-CPC increased by 6.9% compared with S-CPC (Standard CPC, S-CPC). Solar ELE-CPC system with such heat collection performance has a good application prospect in the fields of material drying, building heating, seawater desalination and so on.

Multi-Objective Optimization Algorithms for a Hybrid AC/DC Microgrid Using RES: A Comprehensive Review

Optimization methods for a hybrid microgrid system that integrated renewable energy sources (RES) and supplies reliable power to remote areas, were considered in order to overcome the intermittent nature of RESs. The hybrid AC/DC microgrid system was constructed with a solar photovoltaic system, wind turbine, battery storage, converter, and diesel generator. There is a steady increase in the utilization of hybrid renewable energy sources with hybrid AC/DC microgrids; consequently, it is necessary to solve optimization techniques. Therefore, the present study proposed utilizing multi-objective optimization methods using evolutionary algorithms. In this context, a few papers were reviewed regarding multi-objective optimization to determine the capacity and optimal design of a hybrid AC/DC microgrid with RESs. Here, the optimal system consisted of the minimum cost of energy, minimum net present cost, low operating cost, low carbon emissions and a high renewable fraction. These were determined by using multi-objective optimization (MOO) algorithms. The sizing optimization of the hybrid AC/DC microgrid was based on the multi-objective grey wolf optimizer (MOGWO) and multi-objective particle swarm optimization (MOPSO). Similarly, multi-objective optimization with different evolutionary algorithms (MOGA, MOGOA etc.) reduces energy cost and net present cost, and increases the reliability of islanded hybrid microgrid systems.

Study on the effectiveness of a solar cell with a holographic concentrator

Abstract Solar energy is an important power source. Given this, the development in the direction of converting solar radiation into electrical energy using holographic concentrators is of great importance. The purpose of the study is to determine the electrical characteristics of the solar cell inside the solar cells. To determine the electrical characteristics of the solar cell inside the photovoltaic panel, digital sensors HC-SR04, INA219 and the “Arduino Nano” microprocessor controller were used. The paper presents the results of experimental studies of a solar panel with a holographic concentrator and photovoltaic cells based on gallium arsenide. The high efficiency of converting solar energy into electrical power is shown when dispersing and focusing different wavelengths on a photocell. During elaboration of the obtained volt-ampere characteristics of solar photovoltaic conversion elements, which determine the output power of the photovoltaic panel, the high potential of the developed design of the photovoltaic panel has been revealed. The practical value of the study lies in the fact that with the help of a holographic concentrator it is possible to increase the efficiency of solar energy conversion.

Broadband UV-Excitation and Red/Far-Red Emission Materials for Plant Growth: Tunable Spectrum Conversion in Eu3+,Mn4+ Co-doped LaAl0.7Ga0.3O3 Phosphors.

Broadband ultraviolet (UV) excitation and red/far-red emission phosphors can effectively convert solar spectrum to enhance photosynthesis and promote morphogenesis in plants. Based on the above application requirements, Eu3+ single-doped LaAl1-yGayO3 solid solutions and Eu3+,Mn4+ codoped LaAl0.7Ga0.3O3 phosphors were designed and synthesized in this work. The LaAl0.7Ga0.3O3:0.05Eu3+ (LAG:Eu3+) phosphor exhibits a strong charge transfer band (CTB) excitation and characteristic 5D0 → 7F2 transition red emission (619 nm), which is very similar to the luminescence properties of Eu3+-organic ligand compound (EuL3). Rietveld refinement studies further revealed that the cation substitution disturbs the site symmetry. The optimal Eu3+, Mn4+ co-doped LaAl0.7Ga0.3O3 (LAG:Eu,Mn) phosphor possesses a dual-band excitation spectrum in broadband ultraviolet (UVA, UVB) area and a dual-band emission spectrum within red/far-red area. Under the sunlight radiation, the real-time spectrum of luminous laminated glasses fabricated by coating the LAG:Eu,Mn phosphor shows the percentage of radiant intensity in the red/far-red region significantly increases, suggesting that the phosphor can be a promising candidate for solar spectral conversion in plant cultivation. We believe this work provides a new idea for developing novel broadband ultraviolet excitation and red/far-red emission phosphors.

Finite-temperature properties of CsPbI3 thin films

${\mathrm{CsPbI}}_{3}$ is an inorganic perovskite solar cell material with a band gap appropriate for solar cell applications and photo conversion efficiency greater than 18%. However, this material is also known to undergo many phase transformations within the perovskite structure, starting from a high-temperature cubic phase to a tetragonal phase, leading to a room-temperature orthorhombic phase, with each phase having a different photovoltaic response. The tetragonal phase has been shown to have the highest photoconversion efficiency (18.4%), followed by the cubic phase (17%) and the orthorhombic phase (12.5%). In this work, we use the newly formulated first-principles--based effective Hamiltonian for ${\mathrm{CsPbI}}_{3}$ to investigate the phase transformation sequence in ${\mathrm{CsPbI}}_{3}$ thin films. We investigate the effect of film thickness and substrate strain on the phase transformations and the room-temperature phase. The effect of screening is also investigated. The three perovskite phases previously found in bulk by experiments and by computations were also found to exist in the thin film. It is shown that thickness and substrate strain can stabilize photoactive perovskite tetragonal and cubic phases at room temperature, both of which can be used for solar cell applications.

Economic Feasibility of a Hybrid Microgrid System for a Distributed Substation

A hybrid microgrid system is modelled using HOMER-Pro software for real-time load data and available energy sources at Elapakkam village under Ramapuram substation, Kanchipuram, Tamil Nadu, India. Optimization approaches are applied for the selection of rating of the physical components, including solar PV systems, diesel generators, storage batteries, converters, inverters, and economic parameters such as system cost, fuel cost, and cash flow. The daily community load profile for the year 2018 was estimated based on data from TANGEDCO. Accordingly, the total load demand for the village represented 8760 lines of hourly load. The aim of this paper is to select an optimal-sized and reliable hybrid microgrid system to meet the load demands with available energy inputs. However, a comparison based on the cost of energy (COE) and the penetration of renewable energy is carried out for different case studies in the village with the economic-feasibility analysis of various countries. From this analysis, emissions cannot be completely avoided, they could be minimized by combining existing systems with renewable energy systems.

Green-antisolvent-induced homogeneous phase distribution for efficient and stable MA-free 2D perovskite solar cells

The phase distribution of two-dimensional (2D) perovskites is critical for solar cell power conversion efficiency (PCE). Here, we report a simple green anti-solvent (ethyl acetate, EA) method for obtaining uniform phase dispersion of methylamine (MA)-free quasi-2D Dion-Jacobson (DJ) phase perovskite films (DMePDA)FA3Pb4I13 (n = 4). The films present a more homogeneous phase distribution for their rapid extraction of solvents and the interaction between Pb2+ and the carbonyl group in EA, resulting in a more shining surface, reduced surface-defect density, higher out-plane mobility, and higher conductivity. We obtain a PCE of 18.86 %, which is the highest for MA-free DJ phase 2D perovskite-based devices. In addition, the target devices maintain 85 % and 90 % of their initial values after 1008 h under 85 % relative humidity at 85 ℃ (ISOS-D-3) and continuous illumination at maximum power point (MPP) tracking at ∼ 45 ℃ (ISOS-L-1), respectively.

General and scalable fabrication of plasmonic solar selective absorbers by electrodeposition

Spectrally selective and thermally stable solar absorber attracts lot of attention in solar desalination and other solar thermal applications. Fabricating stable solar selective absorbers (SSAs), in general, and scalability remain a challenge in solar thermal applications. Here, a simple, general, and scalable electrodeposition strategy is demonstrated to fabricate high-performance plasmonic solar selective absorbers, which can generate different metal element (such as Ni, Co, CoNi, and FeCoNi) SSAs on various shape substrates to suit different requirements in solar thermal applications. Taking metal Ni as an example, average solar absorptance αsolar = 0.90 and thermal emittance εIR = 0.08 at 100 °C can be achieved by optimizing the deposition parameters, resulting in a solar thermal conversion efficiency of ηst = 0.82. This plasmonic SSA maintains good stability at 200 °C in the air and 400 °C in the vacuum, respectively. This simple, general, and scalable strategy can be a potential method to fabricate different plasmonic SSAs in solar thermal applications.

Dual non-metal atom doping enabled 2D 1T-MoS2 cocatalyst with abundant edge-S active sites for efficient photocatalytic H2 evolution

Metal–organic frameworks (MOFs) materials featured large specific surface area, unique porous structure and highly crystalline nature which rendered them ideal catalysts in solar light conversion. Generally, the catalytic H2 generation activity of the MOFs was rather low which restricted its application. The effective co-catalyst introduction could enhance its overall performance via reducing the overpotential of hydrogen production while facilitating charges transfer and increasing reactive sites. Herein, an two-dimensional (2D) O,P–MoS2 nanosheets cocatalyst with adequate edge-S active sites and high 1T-phase content were fabricated via co-doping of O and P atoms. Rational coupling the 2D O, P–MoS2 nanosheets with 2D NH2-MIL-125(Ti) nanoplate can afford greatly improved photocatalytic H2 production rate of 339.3 μmol⋅g−1⋅h−1, which was 11.6 and 6.7 times of pure NH2-MIL-125(Ti) and NH2-MIL-125(Ti)/commercial MoS2 composite, respectively. DFT calculation revealed that the edge-S serve as the active sites for H∗ adsorption rather than the plane-S and O sites in O, P–MoS2 or the O and S sites in O–MoS2. Compared with the commercial MoS2 with completely 2H-phase, the dual-doping can create higher-density unsaturated edge-S atoms and more 1T phase which can improve the reactivity of NH2-MIL-125(Ti) via inducing the breaking of Mo–S bonds and providing higher electrical conductivity. Dual non-metal atom doping of MoS2 cocatalyst featured abundant edge-S active centers and high concentration of 1T-phase offered a facile and effective method to developing highly efficient catalysts toward solar-energy conversion.

Experimentally validated numerical model of multi-spectral bands radiative transport in solar receiver/reactor with photo-active porous absorber reacting media

Solar energy efficient utilization such as solar thermal energy storage and thermochemical conversion technologies is an effective way of closing carbon cycles with systematic green environmental remediation. Understanding the complexity of induced light with its spectrum and intensity feature is crucial for the further optimization of the solar system using a more advanced concept such as photothermal catalysis. This study discussed the radiation transfer processes in detail and clarified the principles and assumptions underlying the photothermal effect in the solar receiver/reactor. In addition, the phenomenon of radiation absorption through the porous interface is discussed and the solution of the equivalent surface is given out. Based on the above discussion, a two-bands numerical model is established with various numerical methods to adapt the properties of different surfaces and irradiation sources. The numerical model is validated by experimental data and used to estimate both spectra and intensity transfer characteristics through the solar reactor. The analysis of optimal operation condition, distribution coefficient, spectral feature of glasses, and thermal-optical performance are presented based on advanced numerical model. This study deepens the understanding of radiative transfer mechanisms in solar energy conversion systems and provides pioneering theoretical guidance with an advanced numerical method for the further optimization of a system-level photothermal catalysis process.

Visible DC approach by controlling the UV light in (Eu3+/Tb3+) co-activated TBZN glasses for w-LEDs and a-Si solar cells

Borotellurite (TBZN: TeO2–B2O3–ZnO–Na2O) glasses co-activated with Eu3+ and Tb3+ ions were fabricated by a melt quenching method to know their ability for white light sources and solar converters. Amorphous nature, morphology, elemental mapping of the chemical composition, and functional groups of glasses were investigated. The down conversion (DC) process was studied on the luminescence characteristics of Eu3+/Tb3+ co-activated TBZN glasses by ultraviolet light (UV:351 & 378 nm) conversion and these glasses exhibit the characteristic red (5D0→7F1,2,3,4) luminescence of Eu3+ along with green (5D4→7F5) and blue (5D4→7F6) luminescence of Tb3+ ions in the visible region. Upon 378 nm of UV radiation, the co-activating of Tb3+ with Eu3+ ions improves the green and red DC emissions by 2 and 4 orders of magnitude due to energy transfer (ET) from Eu3+ to Tb3+, respectively. The evidence of ET: Eu3+ → Tb3+ is stated by the declining of red emission (%) and decay times from the 5D0 level of Eu3+ ions, and the reduction in decay times was confirmed to be dipole-dipole interaction in the means of Reisfeld and Dexter's ET process. The solar spectral performance of the excitation and de-excitation spectra of (Eu3+/Tb3+):TBZN glass system is imparted with the standard solar spectrum. Results are also discussed in terms of integrated intensity of red to green emission in (%), critical transfer distance (Rc), (x, y) color coordinates, correlated color temperatures (CCT), color purity (CP), and quantum efficiency (ηQE) values to discriminate the potentiality of (Eu3+/Tb3+):TBZN glass system in white light emitting diodes and solar cells.