Vegetables and herbs play a central role in the human diet due to their low fat and calory content and essential antioxidant, phytochemicals, and fiber. It is well known that the manipulation of light wavelengths illuminating the crops can enhance their growth rate and nutrient contents. To date, it has not been easy to generalize the effects of LED illumination because of the differences in the plant species investigated, the measured traits, the way wavelengths have been manipulated, and the plants’ growing environments. In order to address this gap, we undertook a quantitative review of LED manipulation in relation to plant traits, focusing on vegetables and herbs. Here, we use standardized measurements of biomass, antioxidant, and other quantitative characteristics together with the whole range of the photosynthetic photon flux density (PPFD). Overall, our review revealed support for the claims that the red and blue LED illumination is more reliable and efficient than full spectrum illumination and increases the plant’s biomass and nutritional value by enhancing the photosynthetic activity, antioxidant properties, phenolic, and flavonoids contents. Although LED illumination provides an efficient way to improve yield and modify plant properties, this study also highlights the broad range of responses among species, varieties traits, and the age of plant material.

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Based on the first-principles density functional theory, Janus WXY (X ≠ Y = S, Se, and Te) trilayer homostructures for different stacking patterns are studied in this work to analyze their appropriateness in fabricating photovoltaic (PV) devices. A total of fifteen trilayer homostructures are proposed, corresponding to the suitable five stacking patterns, such as AAA, AA′A, ABA, AB′A, and A′BA′ for each Janus WXY (X ≠ Y = S, Se, and Te) material. Structural and energetic parameters for all the fifteen structures are evaluated and compared to find energetically stable structures, and dynamic stability is confirmed by phonon dispersion curves. All these configurations being homostructure, lattice mismatch is found to be very low (∼0.05%), unlike heterostructure, making them feasible for optoelectronics and PV applications. WSSe AAA, WSSe AA′A, and WSeTe AA′A are dynamically stable along with negative binding energy and show type-II band alignment, enabling effective spatial carrier separation of photogenerated carriers. The optical properties of dynamically stable WSSe AAA and WSSe AA′A structures are also calculated, and the absorption coefficients at the visible light region are found to be ∼3.5 × 10 5 cm –1 , which is comparable to the perovskite material absorption coefficient. Moreover, we have compared the optical characteristics of dynamically stable WSSe AAA and WSSe AA′A structures with their monolayer structures to realize the significance of stacking trilayer structures. Electrical properties such as mobility and conductivity for dynamically stable WSSe AAA and WSSe AA′A structures are evaluated to suggest them as a probable efficient material in PV technology.

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Recently, semiconductor photocatalysts for green hydrogen (H2) fuel require two-dimensional (2D) material with semiconducting direct bandgap and enhanced visible light absorptions. In this study, the first-principles calculation of the 2D layered nanostructure of SnGe2N4 is presented for photocatalysis applications, which has a direct bandgap of 1.73 eV/2.64 eV (Perdew–Burke–Ernzerhof/Heyd–Scuseria–Ernzerhof with generalized gradient approximation) with enhanced optical absorptions. The structure is checked to confirm the chemical formidability and dynamical steadiness by formation energy calculations and phonon dispersions. To attain the tunability of electronic and optical properties, biaxial strains, together with tensile and compressive strains, are incorporated, and it is found that compressive strain widens the bandgap, whereas tensile strain causes bandgap reduction. Biaxial strains also improve the optical absorption and the highest absorption coefficient is obtained at ∼1.47 ⨯ 105 cm−1 for 6% compressive strain, comparable to conventional perovskite materials. However, in the visible spectrum, the highest absorption coefficient is obtained for 6% tensile strain. The calculated photocatalytic band edges suggest that this material has sufficient kinetic overpotential for photo redox at compressive strains in both pH = 7 and pH = 0. In addition, the spatial carrier separation is achieved due to having a large intralayer effective potential deviation of ∼6.96 eV, as well as intralayer spatial atomic group contribution in the valance band maximum and conduction band minimum. Conclusively, the analysis in this study can be a theoretical background of this layered nanostructure as a potent photocatalyst for water splitting.

An organic solar cell (OSC), competitive with traditional one (Si-based), draws attention to future renewable energy sources due to its low-cost and continually rising efficiency. The tandem or multijunction structure undoubtedly offers an efficient way to boost the performance of OSCs. This work has explored the optical modeling of different organic photoactive materials to identify the potential materials for efficient tandem structure. The performance of double, triple, and quadruple junction tandem OSCs with suitable bandgaps has been analyzed with photoactive materials. The absorption efficiency enhances considerably using the thickness optimization of each subcell in tandem structures. Current matching in all subcells, an essential factor for efficient device operation, is taken into account while optimizing tandem structures. The quadruple design can achieve better photovoltaic performance than double or triple junction devices. The efficiency predicted from our proposed quadruple structure is ~15.45%, with a short-circuit current density, JSC of ~9 mA/cm 2 and an open-circuit voltage, VOC of ~2.64 V. These results are one of the high-performance in terms of organic photovoltaic (OPV). Therefore, the above findings indicate that OSCs are very potential for future photovoltaic applications.

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In this work, the effects of AlxGa1-xAs cap and passivation (such as SiO2, Si3N4, and HfO2) layers on the performance of InGaAs/GaAs-based quantum dot intermediate band solar cells (QDIBSCs) have been studied. The low surface recombination rate of ~10 3 per cm 3 s is achieved by optimizing the composition, x = 0.40, and thickness (200 nm) of the AlxGa1-xAs cap layer. The optical reflectance is also evaluated for devices with different passivation. The solar cell with Si3N4 shows the lowest reflectance of 10.53%. The photogeneration rate has been enhanced at the quantum dot region because of the improvement of the photocurrent provides by both cap and passivation layers. There is also an increment found in the average external quantum efficiency of 39.56% as compared to that of the bared conventional QDIBSC. As a result, the solar cell, with both Al0.40Ga0.60As cap and Si3N4 passivation layers, shows the conversion efficiency of 27.8%, which is higher than that of 21.6% for conventional In0.53Ga0.47AS/GaAs-based QDIBSC. These results indicate that GaAs-based QDIBSCs with both Al0.40Ga0.60As cap and Si3N4 passivation layers are promising for next-generation photovoltaic applications.