Full-spectrum Solar Energy Research Articles

Significantly enhanced photothermal catalytic hydrogen evolution over Cu2O-rGO/TiO2 composite with full spectrum solar light

Reduced graphene oxide (rGO) has conspicuous photothermal characteristics in photothermal applications. Thus in our previous work, we used reduced graphene oxide (rGO) supported titanium dioxide (TiO2) nanocomposite (rGO/TiO2) to absorb the ultraviolet and infrared light in the photothermal hydrogen evolution process. In order to make use of the full spectrum solar energy into other clear energy, the visible light should be also considered in following research. Herein, we report a cuprous oxide (Cu2O) decorated reduced graphene oxide (rGO) supported titanium dioxide (TiO2) (Cu2O-rGO/TiO2) catalysts, which can absorb full spectrum solar light in an innovative way. The Cu2O-rGO/TiO2 catalyst is synthesized through a one-step hydrothermal method. The rates of hydrogen evolution are 17800 μmol·g-1h−1 under photothermal condition (90°C), 3800 μmol·g-1h−1 under photocatalysis condition only (25°C) and 0 μmol·g-1h−1 under thermal catalysis condition only. The result of photothermal catalytic hydrogen evolution rate is about 4.7 times that of the sum of the photocatalytic and thermal reactions. The photothermal synergetic effect promotes the photo-generated electron-holes separation through the rGO due to the temperature rising, and accelerates the reaction rates on the catalyst surface in hydrogen evolution process simultaneously. This work could provide us a new promising way for the conversion of full spectrum solar energy to hydrogen energy.

A concentrated solar spectrum splitting photovoltaic cell-thermoelectric refrigerators combined system: Definition, combined system properties and performance evaluation

Currently, a concentrated solar spectrum splitting photovoltaic cell driven semiconductor thermoelectric refrigerator has no relevant report. In this work, a new style model of the concentrated solar spectrum splitting photovoltaic cell-thermoelectric refrigerators (CSSPV-TERs) combined system is established. On the basis of numerical calculation and theoretical study in detail, the influences of the critical parameters on the property of the CSSPV-TERs combined system are analyzed and evaluated. The total efficiency of the CSSPV-TERs combined system is 23.4%. Meanwhile, the current density J, structural factor c and numbers of thermoelectric devices N has been optimally selected to obtain the best COP. The three critical optimal parameters, N = 7, J = 11.7 A/cm2, and c = 0.000125 cm−1, of the CSSPV-TERs combined system can be obtained, which cause the maximum COP, i.e., COPmax = 0.078. The maximum COP and total efficiency of the CSSPV-TERs combined system are superior to other thermoelectric refrigeration combined systems. The research results and new model not only can provide a valuable reference and theoretical support for the optimal design of the novel solar cell driven thermoelectric refrigeration system, but also improve the conversion efficiency of the combined system by efficiently utilizing full-spectrum solar energy.

Salt-resistant Schiff base cross-linked superelastic photothermal cellulose aerogels for long-term seawater desalination

Solar steam generators (SSGs) that continuously supply clean water resources under solar radiation have been recognized as a sustainable approach to mitigate the global water and energy crisis. However, most SSGs currently face the accumulation of salt on the surface during long-term seawater desalination, which hinders the water supply and vapor escape and significantly reduces the evaporation efficiency. Inspired by the porous water channels of reverse transportation, the SSG (PPy@PEI@A-CNF aerogel) with superelastic and photothermal properties was obtained by the Schiff base reaction of aldehyde-based cellulose nanofibers (A-CNF) and polyethyleneimine (PEI) and freeze assembly, and further in-situ polymerized with polypyrrole (PPy). This aerogel with porous hierarchical structure performed outstanding mechanical robustness (89.9% strain remaining after 100 compress-release cycles), ultra-low density (0.021 g cm−3) and thermal conductivity (0.042 W m−1 K−1), high porosity (97.72%) and full spectrum solar energy absorption (98.4%). Moreover, the aerogel could be used for solar-driven water evaporation, and its evaporation rate and efficiency were as high as 1.66 kg m–2h−1 and 94.62% under 1.0 sun. Owing to the rapid re-dissolution of the salt in the reverse transport of macroporous structure, the aerogel exhibited excellent salt-resistant and self-desalting properties during long-term seawater desalination, and also showed superior purification effects and reusability. These findings provide a new method for designing reusable macroporous SSGs to meet eco-friendly, efficient and sustainable fresh water access.

Recent progress on black phosphorus quantum dots for full-spectrum solar-to-chemical energy conversion

Semiconductor-based photocatalysis is one of the renewable and sustainable technologies for direct solar-to-chemical energy conversion to tackle the energy crisis and environmental pollution. Since being rediscovered in 2014, black phosphorus (BP), a two-dimensional (2D) layered material, has aroused extensive interests in the scientific community. In particular, 0D BP quantum dots (BPQDs) derived from 2D BP nanosheets have emerged as a promising candidate for full-spectrum solar energy conversion due to their favorable structural, electronic and optical characteristics. Herein, the most recent advances in the preparation of BPQDs and their unique advantages as well as applications in full-spectrum solar-to-chemical energy conversion like water splitting for hydrogen evolution, CO2 photoreduction and organic pollutant removal are highlighted. Further, the challenges and perspectives of BPQDs-based nanostructures on the possible future research directions in solar-driven heterogeneous photocatalysis are discussed, aiming to timely update one of the most active forefronts for the photo(electro)-catalytic community and beyond.

Dual Active Center-Assembled Cu31S16–Co9-xNixS8 Heterodimers: Coherent Interface Engineering Induces Multihole Accumulation for Light-Enhanced Electrocatalytic Oxygen Evolution

The design of low-cost yet highly efficient electrocatalysts plays a critical role in energy storage and conversion reactions. The oxygen evolution reaction (OER) is considered a bottleneck of electrochemical water splitting for hydrogen fuel generation. It is still challenging to extract a high density of charge carriers in noble-metal-free alternative catalysts to facilitate sluggish kinetics. Herein, we report the rational design and coherent interface engineering for combining light-harvesting Cu31S16 with electroactive Co9-xNixS8 (x = 0-9) to form novel Cu31S16-Co9-xNixS8 heterodimers. By delicately controlling the kinetic growth in a seed-mediated growth method, the bifunctional centers, even with two distinct crystal phases, were integrated into a synergistic architecture, which achieved full-spectrum solar energy capture and light conversion to drive and activate the electrochemical reaction. Benefiting from the well-defined structure, high-quality interface, oriented attachment, and optimal Co/Ni bimetal ratio, Cu31S16-Co7.2Ni1.8S8 produces a dramatically reduced overpotential (242 mV at 10 mA cm-2) with a shift of 83 mV under visible-light excitation, achieving a 4.5-fold higher turnover frequency than that of its unirradiated Co7.2Ni1.8S8 counterpart. This enhanced performance also far exceeds commercial RuO2 (358 mV at 10 mA cm-2) and most nonprecious-metal nanocatalysts. Further mechanistic studies reveal that coherent interface engineering leads to a strong photo/electricity coupling effect and efficient spatial charge separation, which induces sufficient hot holes that eventually accumulate at the electroactive sites to accelerate the multihole-involved OER. This work would open up new opportunities for the fabrication of non-noble metal electrocatalysts and management of charge carriers.

Optimum matching of photovoltaic–thermophotovoltaic cells efficiently utilizing full-spectrum solar energy

The production of redundant waste heat limits the performance of photovoltaic cells, so removing waste heat and converting it back into electricity is a promising way to improve the utilization of solar energy. A new concentrated solar spectrum photovoltaic-thermophotovoltaic hybrid system mainly is proposed. Full-spectrum solar energy is split into different parts according to specific requirements. Expressions for the efficiency and power output of the system are derived. The effects of the voltage output and area ratio of the two subsystems, the bandgap energy of semiconductor in the photovoltaic cell, and the solar concentration factor on the system performance are analyzed comprehensively. By optimizing several key parameters, the problem of the optimal matching between two subsystems is solved. The performance characteristics of the system are revealed, and the maximum efficiency and corresponding power output density of the hybrid system are calculated numerically, reaching 47.74% and 31.13W cm−2, respectively, which are 9.190% and 19.25% higher than those of a single photovoltaic cell. The optimal selection criteria of several key parameters are provided. By comparison with other PV-based systems, the proposed system not only maintains a high energy conversion efficiency but also produces a relatively larger power output density.

Near-infrared-activated Z-scheme NaYF4:Yb/Tm@Ag3PO4/Ag@g-C3N4 photocatalyst for enhanced H2 evolution under simulated solar light irradiation

• NaYF 4 :Yb/Tm@Ag 3 PO 4 /Ag@g-C 3 N 4 photocatalyst active in UV–vis–NIR light is prepared. • Ag inhibits the rapid charge-carrier recombination in g-C 3 N 4 by swift injection of e - from Ag 3 PO 4. • NaYF 4 :Yb/Tm supply additional UV–visible photons to Ag 3 PO 4 /Ag@g-C 3 N 4 under solar light illumination. • NIR-inactive NaYF 4 @Ag 3 PO 4 /Ag@g-C 3 N 4 exhibited H 2 evolution rate of 16.32 mmol/g/h. • NIR-active NaYF 4 :Yb/Tm@Ag 3 PO 4 /Ag@g-C 3 N 4 showed H 2 evolution rate of 23.56 mmol/g/h. Upconversion (UC) active photocatalysts that absorb light beyond UV–visible region and catalyse reactions using the collected upconverted (NIR to UV–visible) photon energy have received incredible attention in renewable solar hydrogen production and environmental remediation. In this study, we report a facile synthesis strategy to produce the NaYF 4 :Yb/Tm@Ag 3 PO 4 /Ag@g-C 3 N 4 architectures responsive in full-spectrum solar light by sequentially depositing the Ag 3 PO 4 /Ag nanoparticles and g-C 3 N 4 nanosheets on UC NaYF 4 :Yb/Tm hexagonal disks. The overlapping of UV–visible emissions generated by the core NaYF 4 :Yb/Tm via UC process from the NIR photons in solar illumination and the absorption of Ag 3 PO 4 /Ag@g-C 3 N 4 shell allows additional photons to supplement the charge carrier separation in Ag 3 PO 4 /Ag@g-C 3 N 4 , which is confirmed by the photoelectrochemical measurements. The presence of metallic Ag inhibits the rapid recombination kinetics in g-C 3 N 4 through swift injection of electrons from Ag 3 PO 4 , thus redeeming more excited electrons in g-C 3 N 4 with high reducing power for H 2 production. The NaYF 4 :Yb/Tm@Ag 3 PO 4 /Ag@g-C 3 N 4 demonstrated 23.56 mmol/g/h photocatalytic H 2 evolution rate, which is 2.6 and 1.4 times higher compared to NaYF 4 :Yb/Tm@Ag 3 PO 4 /Ag (9.05 mmol/g/h) and NIR inactive NaYF 4 @Ag 3 PO 4 /Ag@g-C 3 N 4 (16.32 mmol/g/h) photocatalysts, respectively. Further, NaYF 4 :Yb/Tm@Ag 3 PO 4 /Ag@g-C 3 N 4 photocatalyst H 2 production activities under the illumination of separate NIR, visible, and UV lights are evaluated. The distinctive synthesis approach and underlined photocatalytic H 2 evolution mechanisms have the implications for rationally designing highly efficient UC-based broadband photocatalysts for harvesting full-spectrum solar energy.

Upconversion hollow nanospheres CeF3 co-doped with Yb3+ and Tm3+ for photocatalytic nitrogen fixation

Solar driven nitrogen (N2) fixation to synthesize ammonia is a potential alternative for the traditional Haber-Bosch approach to meeting industrial demand, but is largely hampered by the difficulties in the harvesting of solar energy and activating inert N2. In this work, hollow CeF3 nanospheres co-doped with activator Tm3+ and sensitizer Yb3+ (Yb3+:Tm3+:CeF3) were prepared by microwave hydrothermal method. The product was employed as a catalyst for photo-driven N2 fixation by adjusting the molar ratio of Ce3+:Yb3+:Tm3+. Results show that the porous hollow structure enhances the light-harvesting by physical scattering and reflection. In addition, heteroatom doping generates abundant fluorine vacancies (FV) which provide abundant active sites for adsorption and activation of N2. The sample with molar ratio of CeF3:Yb3+:Tm3+ at 178:20:2 demonstrates the highest utilization of solar energy attributed to the strongest upconversion capability of near-infrared (NIR) light to visible and ultraviolet (UV) light, and the NH4+ concentration achieves the highest value of 15.06 μmol/(gcat∙h) under simulated sunlight while nearly 6.22 μmol/(gcat∙h) under NIR light. Current study offers a promising and sustainable strategy for the fixation of atmospheric N2 using full-spectrum solar energy.

Solar-driven low-temperature reforming of methanol into hydrogen via synergetic photo- and thermocatalysis

Low temperature and efficient hydrogen production from methanol is crucial in development of energy technology. Here a synergetic approach of photo- and thermocatalysis of coupling photocatalysis and thermocatalysis within the full spectrum is proposed to achieve efficient conversion of methanol to hydrogen. The composite copper/zinc/zirconium (Cu/Zn/Zr) oxide nanocatalysts are prepared and firstly utilized in synergetic photo- and thermocatalysis. Combine with the effect of the catalyst component and mass ratio on optical absorption, Cu/Zn/Zr (70:23:7) oxide nanocatalysts with full-spectrum absorption have best performance of synergetic photo- and thermocatalysis. Meanwhile, the synergetic photo- and thermocatalysis not only has better performance than either single photocatalysis or thermocatalysis, but also takes place at a relatively low temperature (130 °C). Under irradiation of 16 suns, the solar-chemical conversion efficiency reaches 45.6%. Photo-generated carriers further promote thermocatalysis, which explains the reaction mechanism of the synergetic photo- and thermocatalysis. The catalytic route in full spectrum can provide some references for future energy storage and utilization. • A novel approach of synergetic reforming of methanol into hydrogen is proposed. • The synergetic photo- and thermocatalysis utilizes full-spectrum solar energy. • The synergetic catalysis is superior to single either photocatalysis or thermocatalysis. • The proposed solar-driven reforming approach can be realized at 130 ℃.

Modification of graphitic carbon nitride by elemental boron cocatalyst with high-efficient charge transfer and photothermal conversion

• Elemental boron (EB) was applied as a cocatalyst for photocatalysis. • The photothermal effect of EB lead to the increase of reaction temperature. • Increased temperature resulted in better molecular collision and charge transfer. • The load of EB modulated band structure and enhanced the charge separation. Photocatalysis is considered as a promising method to degrade pollutants with clean and readily available energy source. Great efforts have been devoted to improve solar energy utilization of the photocatalyst. Herein, we report that elemental boron (EB) nanoparticle can act as an advanced bi-functional cocatalyst for photocatalysis with high solar energy utilization. As a photothermal material, EB could convert long-wavelength light energy to heat to increase the reaction temperature and accelerate the photocatalytic reaction. Moreover, the strong electronic interaction between EB and graphitic carbon nitride altered band structure and also suppressed the recombination of charge carriers. Benefiting from these, EB decorated graphitic carbon nitride exhibited dramatic improvement in photocatalytic degradation of sulfamerazine under the simulated sunlight. This work not only reveals the hidden talent of elemental boron as an advanced bi-functional cocatalyst, but also provides an alternative strategy for efficient full-spectrum solar energy conversion.

Mussel-inspired photothermal synergetic system for clean water production using full-spectrum solar energy

Facing the long-term shortage of global water resources, the use of solar energy for desalination and wastewater treatment has always been the focus of human exploration. Here, inspired by mussel-chemistry, we designed a functional photothermal-photocatalysis system based on Cu foam with abundant marigold-like CuO nanoflowers and Prussian blue (PB) nanoparticles. This superhydrophilic composite material (CuO@PDA/PB) has superior full-spectrum solar energy absorption (300–2500 nm), which achieved interfacial heating under solar radiation to generate stable water vapor. Besides, superhydrophobic CuO@PDA/PB with self-floating properties and Janus CuO@PDA/PB with asymmetric wettability and anti-turnover ability were prepared to systematically compare the effects of wettability on solar energy utilization. We conclude that the hydrophilicity of the sample and the strong capillary pumping effect are more conducive to water transmission, and the superhydrophilic CuO@PDA/PB has a higher evaporation rate (1.39 kg m–2 h−1) and efficiency (87.10%) than other samples under 1.0 sun. Importantly, the superhydrophilic CuO@PDA/PB with excellent salt-tolerance and antifouling property can also be used for the purification of the saline solution, oily wastewater and dyeing effluents via the solar-driven water evaporation. Moreover, CuO@PDA/PB possessed superior adsorption and photocatalytic degradation ability for the organic dyes in dyeing wastewater. Therefore, this solar-driven superwetting functional material provides an expandable and cost-effective platform for seawater desalination and sewage purification.

Ultra-thin dark amorphous TiOx hollow nanotubes for full spectrum solar energy harvesting and conversion‡

Dark titania (TiOx) have been widely used for solar energy harvesting and conversion applications due to its excellent light absorbing performance throughout the ultraviolet to near infrared wavelength band, low cost, and non-toxic nature. However, the synthesis methods of dark TiOx are usually complicated and time-consuming. Here we report a facile and rapid method to fabricate dark amorphous TiOx (am-TiOx) hollow nanotube arrays on nanoporous anodic alumina oxide (AAO) templates using atomic layer deposition. Systematic investigation was performed to demonstrate that Ti3+ and O- species in the am-TiOx ultra-thin films, as well as the spatial distribution of these am-TiOx ultra-thin films on the vertical side walls of AAO templates are two major mechanisms of the black color. Importantly, the film deposition took ~18 min only to produce the optimized ~4‐nm‐thick am-TiOx film. Representative applications were demonstrated using photocatalytic reduction of silver nitrate and photothermal solar vapor generation, revealing the potential of these ultra-thin dark am-TiOx/AAO structures for full spectrum solar energy harvesting and conversion.

One of the most efficient methods to utilize full-spectrum solar energy: A photovoltaic-thermoradiative coupled system

Solar photovoltaic cells are widely used in many aspects, but a mass of solar energy cannot be utilized, resulting in much waste heat being dissipated into the environment, which limits the performance of photovoltaic cells. To improve the utilization of solar energy, a novel model of the concentrated solar spectrum photovoltaic-thermoradiative coupled system is established, where main irreversible losses in the system are considered. Expressions for the power outputs and efficiencies of two subsystems and coupled system are derived. The effects of the voltage outputs and bandgap energies of two cells, area ratios of different units, and the concentration factor on the performance of the coupled system are investigated in detail. The maximum efficiency and corresponding power output density of the coupled system are numerically calculated. The optimal selection criteria of the main parameters affecting the systemic performance are provided. Two subsystems are optimally matched. The performance characteristics of the coupled system are revealed. Compared with the photovoltaic cell and thermoradiative cell alone, the proposed system has a large efficiency enhancement. Compared with other photovoltaic-based coupled systems, the proposed system can be operated at low solar concentration and the maximum efficiency can attain 44.91%, which has a significant efficiency improvement.

Thermodynamic analysis of a combined cooling, heating, and power system integrated with full-spectrum hybrid solar energy device

This paper proposes a combined cooling, heating, and power system integrated with full-spectrum hybrid solar energy device containing molecular solar thermal system and solar water heating system to improve solar energy utilization efficiency. This system comprehensively integrates solar energy, fuel chemical energy and waste heat energy based on methanol decomposition to optimize energy utilization method. The thermodynamic models of components are established and the system evaluation indicators are presented. Based on a rated power of 834 kW, the thermodynamic performances under the design conditions were simulated and analyzed using Engineering Equation Solver, and the Sankey diagrams of energy and exergy flows were obtained in the respective cooling and heating modes. The results indicated that the solar energy share reaches 45.07%, and the energy and exergy efficiencies in cooling mode are 70.65% and 26.59%, respectively. They are increased by 1.52% and 1.92% in heating mode, respectively. The influences of various solar irradiation and power load ratio on system performances are discussed. The results indicate that the power load ratio and direct normal irradiance have positive impacts on energy and exergy efficiencies whereas they have negative impacts on solar energy share. Compared to the conventional methanol direct-fired system, the primary energy saving ratio and carbon dioxide emission reduction ratio of the proposed system reaches 16.20% and 16.14%, respectively.

Exponentially self-promoted hydrogen evolution by uni-source photo-thermal synergism in concentrating photocatalysis on co-catalyst-free P25 TiO2

The concentrating photocatalysis (CPC) to produce hydrogen can be considered as a promising strategy for cooperative utilization of light and heat of full-spectrum solar energy. However, its fundamental mechanism remains elusive and controversial. Here, the P25 TiO2 photocatalyst, which is optimized kinetically and thermodynamically under 36 × sun irradiation (1 × sun = 1 kW m−2), exhibits ultrahigh co-catalyst-free H2 evolution rate (235.8 μmol h−1), which is 1212 times of that in the conventional photocatalysis (PC) under 1 × sun irradiation as the benchmark. Moreover, hydrogen evolution has been identified to be exponentially correlated to reaction time (throughout the growing and stable temperature stages) and irradiance under Xe lamp and sunlight, respectively. These attractively superlinear characteristics of hydrogen evolution can be attributed to the uni-source photo-thermal synergism of accelerated carrier transfer rate by the high-density heat flux and broadened carrier transfer channel by the high-density photon flux. This work highlights the novel reaction characteristics and mechanisms for enhanced hydrogen evolution in CPC, thus provides new guidance to the performance improvement for conventional PC.

Multi-resonant refractory prismoid for full-spectrum solar energy perfect absorbers.

In this work, a feasible way for perfect absorption in the whole solar radiance range is numerically demonstrated via the multiple resonances in a 600-nm-thick refractory prismoid. Under the standard AM 1.5 illumination, the measured solar energy absorption efficiency reaches 99.66% in the wavelength range from 280 nm to 4000 nm, which indicates only a rather small part of solar light (0.34%) escaped. The record harvesting efficiency directly results from the near-unity absorption for the multi-layer refractory resonators, which can simultaneously benefit from the multi-resonant behaviors of the structure and the broadband resonant modes by the material intrinsic features. The absorption including the intensity and frequency range can be adjusted via the structural features. These findings can hold wide applications in solar energy related optoelectronics such as the thermal-photovoltaics, photo-thermal technology, semiconductor assisted photo-detection, ideal thermal emitters, etc.

Thermodynamic evaluation of a concentrated photochemical–photovoltaic–thermochemical (CP-PV-T) system in the full-spectrum solar energy utilization

In most concentrated photovoltaic–thermal systems, solar energy that cannot be used by photovoltaic cells is recycled for the thermal process. The unutilized energy is converted into thermal energy for driving other processes. This increases irreversible losses and restricts the efficient utilization of high energetic photons. To address these challenges, a concentrated photochemical–photovoltaic–thermochemical system is proposed to use the full spectrum of solar energy more efficiently. Photons with photonic energy significantly higher than Eg (the bandgap of photovoltaic cells) are used in the photochemical process, and the below-Eg loss of photovoltaic cells is recycled to provide heat for the thermochemical process. The proposed system realizes the cascade utilization of the full-spectrum solar radiation and can use high-energy photons more efficiently. The irreversible loss from the proposed system is decreased, resulting in higher solar utilization efficiency. The numerical results clearly show that the proposed system outperforms concentrated photovoltaic systems, concentrated thermochemical systems, and concentrated photovoltaic–thermochemical systems. The solar utilization efficiency of high-energy photons (before 600 nm) is increased from 44.01% (of common concentrated photovoltaic–thermal systems) to 80.68%. The total solar utilization efficiency in the proposed system attains 66.95% under the design condition.

Site- and Spatial-Selective Integration of Non-noble Metal Ions into Quantum Dots for Robust Hydrogen Photogeneration

Summary Artificial photosystems consisting of semiconductor quantum dots (QDs) and non-noble metal ions (e.g., Fe2+, Co2+, Ni2+) show intrinsic advantages in efficient and cost-effective hydrogen (H2) evolution. However, well-controlled integration of these metal ions into ultra-small QDs is a major challenge. Here, we present a two-step strategy to realize site- and spatial-selective integration of earth-abundant Fe2+ ions in CdSe QDs; i.e., CdSe QDs are modified with a thin and anisotropic ZnS shell, and partial Zn2+ ions are selectively substituted by Fe2+ via cation exchange. The anisotropic ZnS layer not only passivates CdSe core but also works as an ideal medium to intimately anchor Fe2+. The multifunctional CdSe/Zn1−xFexS QD exhibits extraordinary activity and stability toward H2 photogeneration. Specifically, more than 880 mL (∼39,300 μmol) H2 gas is produced from 6 mL of aqueous solution during a consecutive 172 h (>1 week) experiment, thus achieving a turnover number of >600,000 per QD.

Energy-tunable photon-enhanced thermal tunneling electrons for intrinsic adaptive full spectrum solar energy conversion

Considering that the actual terrestrial solar irradiance is dynamically changing with the atmosphere, the overall efficiencies of most current solar cells are much lower than the reported static values that are based on a standard solar spectrum. The realizations of solar cells, which can maintain high efficiency under variable solar irradiance, are necessary for further improvement of solar energy conversion. In this work, a metal-insulator-semiconductor (MIS) structure based photon-enhanced thermionic energy converter (PETEC) has been proposed for intrinsic adaptive full spectrum solar energy conversion. The basic idea is to form the thermionic electron with desired energy by the photon-enhanced thermal tunneling process. Investigations on its fundamental performance indicate that the MIS-PETEC can have an overall output energy improvement of at least 0.8%, 2.5%, and 3% in typical sunny, rainy, and cloudy days compared to the normal PETEC. Additionally, the total output energy over a year can be improved by at least 3%. These results offer an alternate technique for intrinsic adaptive full spectrum solar energy conversion, which is helpful for the development of next generation high performance solar cells.

A concentrating solar power system integrated photovoltaic and mid-temperature solar thermochemical processes

The approach of cascading solar energy utilization provides access to reliable and ample supplies of energy and has thus attracted widespread attention. Currently, the hybridization of a concentrating solar photovoltaic process and a solar thermochemical process is a promising approach. This paper describes and investigates a concentrating solar power system to harvest solar energy. Co-producing photovoltaic electricity and solar thermal fuel is its attractive distinction. The visible spectrum is cast onto concentrating photovoltaics to generate electricity, and the ultraviolet and infrared spectra are used to drive methanol decomposition at approximately 250 °C. A spectral splitting parabolic trough concentrator is developed in which incident solar radiation is first split and then concentrated. Based on the measured optical data of concentrators, photovoltaics and reactor, the solar-to-electricity performance is evaluated in the proposed system. The results show that a satisfied solar-to-electricity efficiency of approximately 31.8% would be realized if monocrystalline silicon photovoltaics is adopted. In comparison to individual systems, the efficiency enhancements of about 15.3% and 6.3% are obtained. The solar-to-electricity efficiency can reach approximately 35.1% by adopting gallium arsenide. Meanwhile, the improved optical performance proves that the approach of first splitting and then concentrating sunlight is feasible and promising. Finally, the results are anticipated to lead to a new approach for improving full-spectrum solar energy utilization and guiding the establishment of a prototype in the near future.