Efficient Solar Energy Harvesting Research Articles

Steering charge flow in hierarchical ZnIn2S4/TiO2/Ti3C2 heterojunction for noble-metal-free photocatalytic hydrogen production

The construction of effective photogenerated charge transfer channels through interface engineering is the key to achieving the highly efficient of photocatalysts. Herein, sandwich-like ZnIn2S4/TiO2/Ti3C2 nanosheets integrated type-II heterostructure with Schottky junction are reasonably fabricated by low temperature in-situ growth method. Benefitting from the intensive visible light absorption of ZnIn2S4, the fast electron transport of TiO2, the rich active sites in Ti3C2, as well as the intimate interface coupling and the matched band alignment among ternary components, enhanced hydrogen production can be achieved with ZnIn2S4/TiO2/Ti3C2 hierarchical photocatalyst under visible light irradiation in the absence of noble metal co-catalysts. The concept of coupling type-II heterostructure with the Schottky barrier can steer the charge flow and boost the charge carrier separation and transfer across the interfacial domain, which may spark new ensemble design for efficient solar energy harvesting and conversion.

Advances in Hierarchical Inorganic Nanostructures for Efficient Solar Energy Harvesting Systems.

The urgent need to address the global energy and environmental crisis necessitates the development of efficient solar-power harvesting systems. Among the promising candidates, hierarchical inorganic nanostructures stand out due to their exceptional attributes, including a high specific surface area, abundant active sites, and tunable optoelectronic properties. In this comprehensive review, we delve into the fundamental principles underlying various solar energy harvesting technologies, including dye-sensitized solar cells (DSSCs), photocatalytic, photoelectrocatalytic (water splitting), and photothermal (water purification) systems, providing a foundational understanding of their operation. Thereafter, the discussion is focused on recent advancements in the synthesis, design, and development of hierarchical nanostructures composed of diverse inorganic material combinations, tailored for each of these solar energy harvesting systems. We meticulously elaborate on the distinct synthesis methods and conditions employed to fine-tune the morphological features of these hierarchical nanostructures. Furthermore, this review offers profound insights into critical aspects such as electron transfer mechanisms, band gap engineering, the creation of hetero-hybrid structures to optimize interface chemistry through diverse synthesis approaches, and precise adjustments of structural features. Beyond elucidating the scientific fundamentals, this review explores the large-scale applications of the aforementioned solar harvesting systems. Additionally, it addresses the existing challenges and outlines the prospects for achieving heightened solar-energy conversion efficiency.

Facilely Modified Nickel-Based Hole Transporting Layers for Organic Solar Cells with 19.12% Efficiency and Enhanced Stability.

Hole transporting layers (HTLs), strategically positioned between electrode and light absorber, play a pivotal role in shaping charge extraction and transport in organic solar cells (OSCs). However, the commonly used poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) HTL, with its hygroscopic and acidic nature, undermines the operational durability of OSC devices. Herein, an environmentally friendly approach is developed utilizing nickel acetate tetrahydrate (NiAc·4H2O) and [2-(9H-carbazol-9-yl)ethyl] phosphonic acid (2PACz) as the NiAc·4H2O/2PACz HTL, aiming at overcoming the limitations posed by the conventional PEDOT:PSS one. Encouragingly, a remarkable power conversion efficiency (PCE) of 19.12% is obtained for the OSCs employing NiAc·4H2O/2PACz as the HTL, surpassing that of devices with the PEDOT:PSS HTL (17.59%), which is ranked among the highest ones of OSCs. This improvement is attributed to the appropriate work function, enhanced hole mobility, facilitated exciton dissociation efficiency, and lower recombination loss of NiAc·4H2O/2PACz-based devices. Furthermore, the NiAc·4H2O/2PACz-based OSCs exhibit superior operational stability compared to their PEDOT:PSS-based counterparts. Of significant note, the NiAc·4H2O/2PACz HTL demonstrates a broad generality, boosting the PCE of the PM6:PY-IT and PM6:Y6-based OSCs from 16.47% and 16.79% (with PEDOT:PSS-based analogs as HTLs) to 17.36% and 17.57%, respectively. These findings underscore the substantial potential of the NiAc·4H2O/2PACz HTL in advancing OSCs, offering improved performance and stability, thereby opening avenue for highly efficient and reliable solar energy harvesting technologies.

Designing umbrella-shaped heat-induced channels for oriented heat transfer in asphalt mixtures

In order to regulate the directional transfer and collection of heat in pavements, a novel solution has been proposed, named Umbrella-Shaped Heat-induced Channels (UHC). This UHC is composed of carbon fibers with high axial thermal conductivity and a heat-induced layer. A finite element heat transfer model is employed to analyze the heat transfer behaviors of asphalt mixtures. And an indoor irradiation experiment is conducted for feasibility verification. The results indicate that enhancing the thickness of the heat-induced layer or increasing the disparity in thermal conductivity between the heat-induced layer and asphalt mixtures can enhance the oriented heat transfer effect of UHC. The heat-induced layer boosts the horizontal heat flux of the UHC by 60.3% compared to the side without the heat-induced layer. This enhancement is attributed to the secondary thermal convergence effect of the heat-induced layer, which further amplifies the thermal induction and heat collection capabilities of UHC. This phenomenon is crucial for achieving directed heat conduction. The designed UHC can enhance the heat transfer efficiency of the asphalt pavement in the designated direction. Furthermore, it can alleviate the heat island effect, address permafrost thawing and high-temperature rutting issues, and enhance the efficiency of solar energy harvesting on pavements.

A cost-effective photothermal superhydrophobic coating with micro- and nano-graded structures for efficient solar energy harvesting

Solar collector coatings can solve the current energy shortage and environmental pollution by converting clean solar energy into thermal energy. However, once the coating is adhered to a liquid, the performance of the solar thermal conversion will be seriously affected. Here, a cost-effective photothermal superhydrophobic coating was designed by modulating the microstructure of a highly solar-absorbing material (MCN), followed by a simple spraying method combined with polyvinylidene fluoride resin (PVDF). The MCN in the coating provides excellent photothermal conversion performance, hence, the surface temperature of the coating can be rapidly increased to 97.5 °C at 1 kW/m2. In addition, the coating achieves a water contact angle (WCA) of 155.79° due to the combined micro-nano structure of MCN and PVDF coupled with the low surface energy of PVDF. More importantly, the coating possesses excellent mechanical properties and can be applied to different substrates. This cost-effective photothermal superhydrophobic coating has promising applications in outdoor environments such as insulated tents and waterproof insulation packaging.

Highly efficient molybdenum nanostructures for solar thermophotovoltaic systems: One-step fabrication of absorber and design of selective emitter

Efficient solar energy harvesting materials or structures have become a topic of great interest in response to the ever-increasing energy demand. Refractory transition metals have been found to exhibit attractive properties in broadband absorptance, making them highly effective in solar thermophotovoltaic (STPV) systems that aim to surpass the Shockley-Queisser limit. Typically, broadband absorbers are made from hybrid materials or complex geometrical structures, which require multi-step fabrication technologies. In this study, we successfully developed a highly efficient broadband absorber based on molybdenum (Mo) nanosheets using a one-step physical vapor deposition process. The nanosheets result in the high absorber efficiencies of 96.1 % for blackbody radiation (BBR) at 5778 K and of 96.4 % for air mass (AM) 1.5 spectrum, and are insensitive to polarization and incident angle. After annealing at 1650 K for 24 h, the Mo nanosheets absorber demonstrates outstanding thermal stability without compromising the efficiency of the STPV system. To complete the STPV system, a selective narrowband Mo-based gratings emitter was further designed with a high emissivity of 96 % at a wavelength of 2.17 μm, resulting in a high PV cell efficiency of 41.8 % around 1723 K. Through a series of theoretical calculations, the proposed STPV system can achieve an overall conversion efficiency of 40.2 % by a trade-off between the structure temperature and the sun concentration. Furthermore, an efficiency of 35.5 % can be achieved at a low temperature of 1073 K with a low solar concentration of 500 suns.The results provide tremendous opportunities for widespread applications of high-performance STPV systems.

Review: wood composites as sustainable energy conversion materials for efficient solar energy harvesting and light management

Review: wood composites as sustainable energy conversion materials for efficient solar energy harvesting and light management

Revolutionizing Energy Harvesting: Harnessing Ambient Solar Energy for Enhanced Electric Power Generation

The escalating demand for sustainable and renewable energy sources has propelled the exploration of ambient solar energy as a pivotal avenue for cleaner power generation. This review paper delves into the intricacies of solar energy harvesting technologies, providing a comprehensive analysis of principles, efficiency metrics, material advancements, and versatile applications. Focusing on the photovoltaic effect as the cornerstone of solar cells, the critical impact of semiconductor material selection and bandgap engineering on efficiency is thoroughly examined. Key performance measures such as fill factor, open-circuit voltage, and short-circuit current are emphasized for their pivotal role in evaluating system efficiency. The adaptability of solar energy solutions is exemplified through diverse applications, spanning from portable electronics to large-scale solar farms. Looking towards the future, this review envisions a promising trajectory for solar energy harvesting, driven by continual advancements in technology, material science, and efficiency measures. The insights gleaned from this comprehensive examination are poised to catalyze the development of more efficient and accessible solar energy harvesting technologies. This, in turn, promises to play a significant role in the global transition towards a greener and more sustainable energy landscape, contributing substantively to sustainability, climate mitigation, and an enhanced quality of life worldwide. Keywords: Solar energy harvesting, solar cells, material selection, panel orientation, storage techniques, system integration, case studies.

Bi/Bi2O3/TiO2 heterojunction photocathode for high-efficiency visible-light-driven lithium-sulfur batteries: Advancing light harvesting and polysulfide conversion

Integrating solar-electrical energy conversion and electrical-chemical energy storage functions within a single device offers a promising strategy for efficient light harvesting, conversion, and storage of renewable solar energy. Herein, we develop visible-light-driven photoelectrochemical Li2S6-based lithium-sulfur batteries (VPLSBs) for simultaneous energy conversion and storage, employing a versatile Bi/Bi2O3/TiO2 photocathode as both a light harvester and redox catalyst. The narrowed band gap of photocathode minimizes photoelectron-hole recombination, enabling efficient light-to-electrical energy conversion. Its energy level alignment with Li-S electrochemical potentials facilitates the photocarriers’ participation in polysulfide conversions, supporting electrical-to-chemical energy storage. Under visible light, the Bi/Bi2O3/TiO2 photocathode exhibits a photoelectrocatalysis effect, enhancing interfacial charge transfer, reducing Li2S deposition resistance, and ensuring stable Li2S plating/stripping. Additionally, the bare photo-charging process achieves an overall energy conversion-storage efficiency of 2.58 %. The VPLSB demonstrates an exceptional specific capacity of 1484 mA h g−1 over 900 cycles, maintaining an apparent energy efficiency of 100.2 % at 0.2 mA cm−2.

Improvement in hot carrier dynamics of all-inorganic halide perovskite CsPbI3 on doping Cu

Hot carrier extraction is crucial for efficient solar energy harvesting, and lead halide perovskite nanocrystals (NCs) are potential candidates for photovoltaic and light-emitting applications. Therefore, swift extraction of hot carriers is an immediate requirement to improve the energy conversion efficiency, which need longer thermalization time. To address this issue, we synthesized nominally Cu-doped CsPbI3 NCs with enhanced structural and optical characteristics compared to undoped CsPbI3 NCs. We investigated the hot carrier dynamics in both the NCs at different fluences using ultrafast transient absorption spectroscopy. Interestingly, we observed very fast thermalization at higher fluences that indicated breaking of the phonon bottleneck. On the contrary, doped NCs preserved the effects and decayed over a longer period of time possibly due to increase in size and introduction of shallow trap states of Cu 3d and Cu 4s electrons in the conduction band, as computed using density functional theory. Notably, as the carrier–carrier interaction increased, we observed a dominating bandgap renormalization in the doped system compared to the undoped system. Overall, our studies improve the understanding of Cu doping in enhancing the hot carrier dynamics in perovskites and open possibilities for further investigation in the quantum phenomenon of these materials.

Enhancing efficient solar energy harvesting: A process-in-loop investigation of MPPT control with a novel stochastic algorithm

PV systems currently generate 4% of the world's energy needs, and their share is growing quickly. The maximum power point tracking (MPPT) is a complex non-convex optimization problem because the electrical characteristics of the PV model are nonlinear. Changes in temperature, partial shading (PS), and irradiance levels can all affect the amount of power that can be extracted from the solar system. Therefore, in this work, a novel energy valley optimizer (EVO) based MPPT algorithm is suggested to extract maximum power from solar. The classical perturb and observe (P&O), whale optimizer algorithm (WOA), cuckoo search algorithm (CSA), and particle swarm optimization (PSO) algorithms are all compared to EVO. Five case studies, including a field atmospheric data study, partial shading, variable temperature, and irradiance, are used to conduct in-depth analytical and statistical analysis. Furthermore, the successful verification of the MPPT control algorithm on the real microcontroller (Arduino MKRZERO board) through the PIL test is a critical milestone in this research. Quantitative, comparative, statistical and experimental results indicate that the proposed EVO-based MPPT achieves superior performance through 30% quicker tracking time and 80% faster settling time, which result in 4–8% higher power efficiency. The results indicate that the suggested MPPT controller successfully addresses the shortcomings of the current MPPT methods.

Experimental analysis of the thermal performance of traditional parallel tube collector (PTC) and cutting-edge spiral tube collector (STC): A comparative study for sustainable solar energy harvesting

FPSC performance has remained low despite technical developments. Innovatively constructing solar energy collecting systems to maximize efficiency needs more investigation. This study examines the thermal performance of a flat-plate solar energy harvesting system using a cutting-edge collector design and hybrid nanofluid. A spiral tube collector (STC) is designed as a single flow tube by replacing the header-connected riser tubes in a parallel tube collector (PTC). By modifying the collector's design, a noteworthy enhancement in thermal performance was achieved. STC's experimental testing shows 18.98%, 28.86%, and 18.97% enhancement in thermal efficiency, exergy efficiency, and energy gains compared to PTC design. STC design reduces pressure drop by 6.25% and entropy generation by 28.86%. The current investigation may help choose an appropriate collector design for efficient solar energy harvesting purposes.

Enhancing solar thermal energy harvesting efficiency and temperature uniformity of Fe3O4 nanofluid in receiver of direct solar thermal collector using dynamic magnetic field

To improve the solar thermal energy harvesting performance (STEHP) according to the receiver depth of a direct absorption solar collector (DASC), the Fe3O4 nanofluid (NF) was used as a working fluid. Besides, an external dynamic magnetic field (MF) was applied to the working fluid, and the effect of the dynamic MF on the heat transfer performance and temperature uniformity of the working fluid was investigated. As a result, with the increase in receiver depth, the STEHP decreased due to the temperature non-uniformity of working fluid and the increase in heat loss at the top part. When the receiver depth was 6 cm, the highest solar thermal energy harvesting efficiency (STEHE) was observed at the concentration of 0.075 wt%. When an external dynamic MF was applied to the 0.075 wt% Fe3O4 NF, the temperature non-uniformity was reduced; therefore, solar energy absorption and storage performance improved significantly. The STEHE using an external dynamic MF increased by 119.6 % compared to DI-water. It was confirmed that applying a dynamic MF to the Fe3O4 NF could significantly improve the STEHP of DASC by enhancing the temperature uniformity within the working fluid and the solar energy absorption performance.

Numerical and experimental study of a novel vacuum Photovoltaic/thermal (PV/T) collector for efficient solar energy harvesting

Photovoltaic/thermal (PV/T) technology can generate electricity and heat simultaneously and improve solar energy harvesting efficiency. However, flat-plate PV/T collectors have strong heat loss in cold conditions and the collected heat is low-grade thermal energy, which limits the practical application of the PV/T collectors on a large scale. Herein, the vacuum environment is introduced to the flat-plate PV/T collector, conductive and convective heat loss are blocked, improving the efficiency and operating temperature of the PV/T collector. In this paper, a novel design of the vacuum PV/T collector has been proposed and fabricated, which maintains both the upper and lower space of the absorber in a vacuum state without additional glass cover causing energy loss. Performance comparison between the vacuum PV/T collector and the air–gap PV/T collector has been conducted, demonstrating that the vacuum condition can decrease the heat loss coefficient by 16.08%. In addition, a combined thermal-electrical mathematical model is constructed and validated. The predicted results reveal that the annual thermal energy outputs of the vacuum PV/T collectors without and with ideal low emissivity coating are 124.88% and 346.58% higher than that of the air–gap PV/T collector when the operating temperature is 50 °C. In summary, the vacuum PV/T collector exhibits great potential in improving thermal performance while slightly reducing the output of electrical energy. This work contributes to extending the working time of the PV/T collector and guides the design of the new generation of highly efficient PV/T collectors.

Anisotropic Black Phosphorene Structural Modulation for Thermal Storage and Solar-Thermal Conversion.

Exploiting novel strategies for simultaneously harvesting ubiquitous, renewable, and easily accessible solar energy based on the photothermal effect, and efficiently storing the acquired thermal energy plays a vital role in revolutionizing the current fossil fuel-dominating energy structure. Developing black phosphorene-based phase-change composites with optimized photothermal conversion efficiencyand high latent heat is the most promising way to achieve efficient solar energy harvesting and rapid thermal energy storage. However, exfoliating high-quality black phosphorene nanosheets remains challenging, Furthermore, an efficient strategy that can construct the aligned black phosphorene frameworks to maximize thermal conductivity enhancement is still lacking. Herein, high-quality black phosphorene nanosheets are prepared by an optimized exfoliating strategy. Meanwhile, by regulating the temperature gradient during freeze-casting, the framework consisting of shipshape aligned black phosphorene at long-range is successfully fabricated, improving the thermal conductivity of the poly(ethylene glycol)matrix up to 1.81Wm-1 K-1 at 20vol% black phosphorene loading. The framework also endows the composite with excellent phase-change material encapsulation capacity and high latent heat of 103.91Jg-1 . It is envisioned that the work advances the paradigm of contrasting frameworks with nanosheets toward controllable structure thermal enhancement of the composites.

A Quantile Functions-Based Investigation on the Characteristics of Southern African Solar Irradiation Data

Exploration of solar irradiance can greatly assist in understanding how renewable energy can be better harnessed. It helps in establishing the solar irradiance climate in a particular region for effective and efficient harvesting of solar energy. Understanding the climate provides planners, designers and investors in the solar power generation sector with critical information. However, a detailed exploration of these climatic characteristics has not yet been studied for the Southern African data. Very little exploration is being done through the use of measures of centrality only. These descriptive statistics may be misleading. As a result, we overcome limitations in the currently used deterministic models through the application of distributional modelling through quantile functions. Deterministic and stochastic elements in the data were combined and analysed simultaneously when fitting quantile distributional function models. The fitted models were then used to find population means as explorative parameters that consist of both deterministic and stochastic properties of the data. The application of QFs has been shown to be a practical tool and gives more information than approaches that focus separately on either measures of central tendency or empirical distributions. Seasonal effects were detected in the data from the whole region and can be attributed to the cyclical behaviour exhibited. Daily maximum solar irradiation is taking place within two hours of midday and monthly accumulates in summer months. Windhoek is receiving the best daily total mean, while the maximum monthly accumulated total mean is taking place in Durban. Developing separate solar irradiation models for summer and winter is highly recommended. Though robust and rigorous, quantile distributional function modelling enables exploration and understanding of all components of the behaviour of the data being studied. Therefore, a starting base for understanding Southern Africa’s solar climate was developed in this study.

Photocatalytic water splitting in the gap between plasmonic gold nanoclusters

Plasmon-mediated photocatalytic water splitting holds promise for efficient solar energy harvesting. Experimental studies have shown that “hot spots” in an assembly of plasmonic nanoclusters, which is the real case for practical applications, are beneficial for photocatalysis, but the interactions between different nanoclusters are difficult to observe by experimental techniques. Theoretical studies, however, have employed the model with a water molecule adsorbed on a single plasmonic metal nanocluster. Here, we employed the representative model of a water molecule placed in the gap between two gold nanoclusters and computationally investigated the effects of the configurations of plasmonic nanoclusters on plasmon-mediated water splitting. Results show that the hot electron transfer mode can be tuned by the plasmonic configurations. Compared to the configuration with only one gold nanocluster, more significant contribution of direct charge transfer was observed for the configuration with two gold nanoclusters, which is attributed to a stronger field enhancement; as a result, the water splitting rate was also enhanced. Results also demonstrate a charge transfer chain from one gold nanocluster to the water molecule and then to the other gold nanocluster, which is tunable by the distances between the water molecule and the gold nanoclusters. This charge transfer chain significantly affected the amount of hot electrons accumulated on the water molecule. Caused by this, the configuration where the water molecule was placed right at the center of the two gold nanoclusters, i.e., the configuration corresponding to the strongest field enhancement, was surprisingly not the most favorable one for the reaction.

Effect of morphological evolution and aggregation of plasmonic core-shell nanostructures on solar thermal conversion.

Achieving high solar energy absorption based on nanofluids (NFs) needs further study in solar photothermal conversion technology. In this work, we performed COMSOL simulations to investigate the solar energy absorption using a core-shell nanostructure composed of the Au core and shell with different materials. The influence of the radius of the Au core, the materials of the shell, and the shell thickness on the solar absorption efficiency factor (SAEF) are systematically studied. The results show that the SAEF of the Au@Li nanoparticle with ratio of 0.5 has the highest SAEF of 1.4779, increasing 1.99 times compared to that of the bare Au nanoparticle of 0.74326 with the same radius. Moreover, the optical properties, electric field distribution, and SAEF of the Au@Li dimer are further evaluated to demonstrate the aggregation effects on SAEF. We find that the SAEF of the Au@Li dimer reaches the maximum of 4.34 with a distance around 1nm, where the LSPR coupling effect in the nanogap is sharply enhanced 700 times irradiated by light with wavelength of 760nm. Finally, the direct absorber solar collector performance demonstrates that Au@Li dimer NFs can collect 93% of solar energy compared to 54% for Au@Li NFs and 51% for Au NFs. This work provides the possibility to achieve more efficient solar thermal conversion, and may have potential applications in efficient solar energy harvesting and utilization.

TiN-based metasurface absorber for efficient solar energy harvesting

Solar absorber, which is widely used in concentrated solar thermal systems and solar photovoltaics, has attracted great attention in recent years. Concentrated solar irradiation not only saves production costs, but also effectively improves the photothermal conversion efficiency of the system. However, the huge radiative heat flux will cause the system temperature to rise rapidly, which poses significant challenges for designing solar absorbers. Here, a metasurface absorber based on cylinder array structure is proposed for efficient solar energy harvesting, using the high-temperature resistant materials TiN and SiO2. The total solar absorption of the absorber is up to 0.94 at wavelengths of 300–2500 nm. The high absorption performance of the metasurface absorber can be explained as the coupling effect of surface plasmon resonance and Fabry-Pérot resonance, which is confirmed by the electric field distribution. Moreover, the effect of geometric parameters on absorption performance is analyzed. Finally, we discuss the influence of incident angle on the solar absorber. We believe this work could deepen the understanding of coupling resonance mode and guide the design of high-temperature solar absorbers.

Stability of Catalytic Centres in Light-Driven Hydrogen Evolution by Di- and Oligonuclear Photocatalysts.

A review. In recent decades, mimicking natural photosynthesis by artificial photocatalysis represented a major research direction with the ultimate goal of reducing fossil fuel consumption through efficient solar energy harvesting. To transfer molecular photocatalysis from the lab scale to an industrially relevant process, it is important to overcome instability problems of the catalysts during light-driven operation. As it is well-known that many of the typically utilized noble metal-based catalytic centres (e. g. Pt and Pd) undergo particle formation during (photo)catalysis and thus switch the whole process from a homogeneous into a heterogeneous one, an understanding of the factors governing particle formation is crucially needed. The review therefore focuses on di- and oligonuclear photocatalysts bearing a range of different bridging ligand architectures for drawing structure-catalyst-stability relationships in light-driven intramolecular reductive catalysis. In addition, ligand effects at the catalytic centre and their implications for catalytic activity in intermolecular systems will be discussed, as will important insights into the future design of operationally stable catalysts.