Solar Energy Materials and Solar Cells最新文献

This work presents a comprehensive numerical evaluation of PERC and TOPCon technologies, focusing on the impact of radiation-induced defects. This assessment is conducted for p-type silicon solar cells as they are intrinsically more resistant to radiation defects. By rigorously calibrating recombination parameters, radiation-induced defect profiles, and other pertinent details, a robust basis is established for an in-depth comparison of the performance characteristics displayed by both architectures under space conditions. The investigation reveals that when utilizing substrates with high doping levels, both PERC and TOPCon cells exhibit nearly identical beginning-of-life (BOL) and end-of-life (EOL) performance. However, with lower substrate doping concentrations, both technologies show improved BOL efficiency. Notably, this enhanced BOL efficiency does not translate into superior EOL efficiency. This distinction in EOL efficiency can be attributed to two primary factors triggered by radiation exposure. Firstly, the emergence of defects leads to a reduction in open-circuit voltage. Secondly, dopant compensation contributes to an increase in series resistance. Specifically, for PERC cells, the challenge of elevated series resistance is further exacerbated by the requirement for majority carriers to traverse both vertically and laterally to reach the rear metal contact. When a robust defect recovery mechanism or resilient cover glass is absent, substrates characterized by lower doping levels display increased susceptibility to the adverse effects of radiation-induced defects and the subsequent dopant compensation. Under these circumstances, the TOPCon technology demonstrates a significant advantage over PERC, particularly for high electron fluence due to its full area contacts for both minority and majority charge carriers.

Smart windows hold promise for mitigating energy demand for indoor heating or cooling. However, VO₂-based thermochromic smart windows face challenges such as high phase transition temperature, limited window color options, and a lack of functional diversity. Herein, we investigated the colorful smart windows utilizing the tungsten-doped VO₂ thin films with the phase transition temperature of approximately 23.5 °C. The surface color of these smart windows can be dynamically adjusted from brown to purple, cyan, yellow, and red by tuning the thickness of the wave-impedance matching layer of HfO₂ film, resulted from the interference effect of the HfO₂ layer and the underlying W_xV_1-xO₂ layer. Moreover, the HfO₂-coated W_xV_1-xO₂ thin film with the HfO₂ thickness of 132 nm demonstrates superior optical performance with a solar modulation ability of 9.35 %, the low-temperature luminous transmission of 36.81 %, and the high-temperature luminous transmission of 38.03 %. In addition, the incorporation of SiO₂ nanoparticles into the HfO₂-coated W_xV_1-xO₂ thin films results in the superhydrophobic property with a water contact angle of 162.1^° due to the formed rough surface, which is favor to the self-cleaning of the windows surface.

Vanadium dioxide has emerged as a promising material for smart windows owing to the temperature-responsive variable near-infrared (NIR) transmittance. Yet, the poor NIR modulation ability challenges its efficiency in thermal management. In this study, by meticulously controlling the oxygen vacancy content at a low level, VO₂ nanoparticles with excellent NIR modulation performance are achieved. Oxygen vacancy (V_O) defects elimination leads to a remarkable decrease of reflectance in the monoclinic (M) phase, dramatically enhancing the near-infrared contrast of VO₂ by 154 %. Density functional theory (DFT) calculations reveal that V_O elimination favors low refractive index in the NIR region. The optimized experiment is carried out to prepare VO₂ nanoparticles with low defects and high crystallinity. It shows the best NIR transmittance contrast at 1500 nm (ΔT_{1500 nm}) of 24.4 %, simultaneously keeping a high luminous transmittance (T_lum) of 79.7 %. This study is believed to provide valuable guidance for the current defect and thermochromic performance study of VO₂.

Photoelectrochemical (PEC) water splitting, which harnesses solar radiation (an infinite energy source) for clean hydrogen production without carbon-dioxide emissions, is an ideal eco-friendly energy technology. The core reactions in PEC water splitting, involving the oxidation and reduction of water, are driven by electron–hole pairs generated through solar energy absorption. Consequently, the light-absorption efficiency emerges as a critical parameter in PEC devices. Conventional thin-film-type photoanodes, however, grapple with limited absorption due to their high reflectance, hindering absorption and carrier separation efficiency. Conversely, moth-eye-structured photoanodes exhibit an anti-reflection effect stemming from their subwavelength structure, markedly enhancing light-absorption efficiency. In this study, we present the design and fabrication of a densely packed moth-eye-structured bismuth vanadate (BiVO₄) (M-BVO) photoanode, which is engineered to possess superior light absorption properties. The photoanode was fabricated via direct printing, electron-beam evaporation, and Vanadium calcination processes. The light absorption of the resulting M-BVO photoanode increased to approximately 92 % within the 300–500 nm wavelength range, with the absorption efficiency (η_abs) surging to 82.9 %. This represents a 23.5 % enhancement compared to its flat BiVO₄ counterparts. Impressively, the photocurrent density of M-BVO reached 2.98 mA cm⁻² at 1.23 V_RHE, 37.6 % higher than that of flat BiVO₄. These results indicate that the PEC efficiency can be significantly increased through moth-eye structuring, emphasizing the indispensable role of nanostructure research in the manufacture of high-efficiency photoanodes.

Silicon-based solar photovoltaics cells are an important way to utilize solar energy. Diamond wire slicing technology is the main method for producing solar photovoltaics cell substrates. In order to reduce production costs and improve the production efficiency, the solar photovoltaics cell substrates silicon wafers are developing in the direction of large size and ultra-thin, and the diamond wire slicing technology is developing in the direction of high wire speed and fine wire diameter. These aspects cause an increase in the fracture probability of silicon wafer during the processing and increase costs. In this paper, a comprehensive review has been conducted on silicon wafer fracture with the latest research. Firstly, the strength characteristics of ideal crystalline silicon are summarized and discussed. The ideal crystalline silicon has a large mechanical strength, and the tensile strength in the non-dissociation direction is more than 10 GPa, while the fracture strength of silicon wafers is only 100 MPa–500 MPa. This is because there is subsurface damage on the wafers during slicing processing. Then the testing methods and statistical methods of silicon wafer fracture strength are introduced. The testing methods mainly include 3-point bending test, 4-point bending test, and biaxial bending test. Collecting load-displacement data during bending test can further calculate the fracture stress of silicon wafers through linear stress analytical formulas and finite element methods. Then, the Weibull function is used for statistical analysis to obtain the fracture strength of the silicon wafer. Finally, the research literatures on the theoretical modeling of silicon wafer fracture strength and the calculation model of silicon wafer fracture probability under different load conditions are introduced. This review contributes to a comprehensive understanding of the mechanical strength degradation and fracture mechanism of silicon wafers, and provides critical insights for future research interests.

We report the hydrothermal deposition of Sb₂S₃ thin film on top of CdS buffer layer, and the fabrication of prototype photovoltaic devices utilizing spiro-OMeTAD as the hole transport layer. The as-deposited films were amorphous, which transformed to polycrystalline after thermal processing. The pristine films were annealed at different temperatures and showed effective recrystallization at 350 °C which resulted in larger grains, intense XRD patterns, and significantly improved device parameters. The obtained V_OC of 795 mV is among the highest reported for a Sb₂S₃ based solar cell. Deep level transient spectroscopy studies detected an electron trap with activation energy 0.61 eV in the pristine annealed absorber, which became deeper (0.66 eV) upon Na incorporation. However, the capture cross-section decreased by an order of magnitude, and the trap density halved. The reduction in the capture cross-section and trap density for the Na-incorporated device coincides with the improved EQE response in the mid- and long-wavelength regions and a 9 % increase in device efficiency. The light intensity dependence of V_OC clearly demonstrated that Na incorporation reduced the trap-assisted recombination and facilitated efficient charge transport in the device.

The current solar cells and modules are marketed according to the behaviour at standard test conditions (STC), however, these devices are more often operated at lower irradiance levels. The dependence on illumination stems mainly from the voltage at the open circuit and at the maximum power point. The latter might also be strongly influenced by serial resistance, but that is more an engineering problem not addressed here. More fundamentally, the voltage is determined by quasi-Fermi levels at the contacts. In the case of unconstrained conductivity between the absorber and electrode, the quasi-Fermi levels are flat, and determined by their splitting in the absorber. Our analysis shows that the modulation doping mechanism working in Si heterojunction solar cell between the doped amorphous Si layer with a higher bandgap and crystalline absorber with a lower bandgap can, for certain parameter settings, lead to strongly depleted contact layer that limits conduction. This is a prerequisite for decoupling the quasi-Fermi level between contact and absorber and offers the possibility for additional voltage increase. Based on this understanding, we simulate a heterojunction solar cell with a varying thickness and doping of amorphous silicon p-type contact. We demonstrate that for a certain combination of thinner or lower-doped contact, higher efficiency at low illumination can be achieved compared to the technological baseline. This is fully in line with the experimental findings. This analysis is crucial not only for using solar cells for indoor applications but also for designing photovoltaic modules optimized for low irradiance, potentially increasing the level of self-sufficiency of buildings.

Building thermal management is responsible for over 40 % of total energy use, of which about 20 % is directly related to the operation of heating. Materials saving energy to heat buildings would contribute substantially to sustainability. In this study, we have developed a series of flame-retardant shape-stabilized phase change composites (PCCs) by incorporating MXene@PTA and flame-retardant phytic acid dicyandiamide (PD) into a waterborne polyurethane framework using a simple vacuum impregnation technique, and their thermophysical properties, photothermal conversion, and flammable retardant performance were systematically studied. It was found that the resulting composite, termed PMWP PCCs, achieved an enthalpy efficiency and relative enthalpy efficiency of 68.66 % and 99.7 %, respectively. And it maintained excellent shape stability even after 180min at 70 °C, which demonstrates effective inhibition of leakage of phase change material. Furthermore, the maximum temperature of PCCs without modified MXene was observed to be around 37 °C, which rose to more than 45 °C after adding modified MXene, indicating higher photothermal conversion performance. Most importantly, compared to pure PEG, the peak heat release rate and total heat release value of the modified phase change composites were found to be reduced by 6.7–35.8 % and 13.2–19 %, respectively. The results suggest that the combination of MXene and PD exhibits a synergistic flame retardant effect, enhancing the flame retardancy. These outcomes underscore the promising application potential of PMWP PCCs in the fields of thermal management and energy storage.

Antimony sulfide (Sb₂S₃) is a promising material for photovoltaic applications because of its high absorption coefficient, environmental friendliness and low cost. Nevertheless, the conversion efficiency of Sb₂S₃ solar cells severely deviates from theoretical predictions, and the interface between CdS and Sb₂S₃ is crucial for the overall performance. In this study, we conducted a highly effective sodium borohydride (NaBH₄) etching to modify the CdS/Sb₂S₃ interface, aiming to improve the device performance. The NaBH₄ etching led to a reduction in surface roughness and an enhancement in the hydrophilicity of the CdS layer, creating a more conducive environment for the subsequent deposition of the Sb₂S₃ absorber layer. Simultaneously, the reduction of cadmium oxide serves to optimize interfacial energy alignment and minimize recombination losses. Ultimately, our full-inorganic Sb₂S₃ solar cells, featuring the configuration FTO/CdS/Sb₂S₃/MnS/Carbon, attain a PCE of 6.26%. This marks a significant improvement of 15% compared to cells without NaBH₄ etching. This study presents a feasible and efficient perspective for modifying the CdS/Sb₂S₃ interface, thereby enhancing the performance of Sb-based solar cells.

Carbonized materials have been reported as potential candidates for the application of solar water evaporation due to their low cost and easy availability. However, the unregulatable internal structures of these evaporators are usually not conducive for achieving high evaporation rates. Herein, foam material with artificial three-dimensional configurations was selected in our work to combine with surface carbonization for improving the evaporation performance. By utilizing pulp foam (PF) as raw material, our present work proposes an easy-fabricated hierarchical evaporator design composed of an upper carbonized pulp foam (CPF) layer and a bottom pristine PF matrix layer. Deposition of polypyrrole (PPy) particles on the carbonized layer was applied for further enhancement on the evaporation performance based on light trapping effect. As a result, the CPF-2PPy evaporator fabricated in our work could achieve an average evaporation rate of 2.56 kg m⁻² h⁻¹ under 1.0 sun illumination during a 10-cycle indoor evaporation experiments. Our work reports a convenient approach to fabricate a highly efficient solar water evaporator based on the simple surface carbonization of PF and the light trapping effect produced by PPy nanoparticles deposited on it.