Solar Energy Materials and Solar Cells最新文献

The study discussed in this publication aimed to develop a perovskite solar cell adapted to operating conditions at reduced temperature and pressure and less than 1 μm thick. The physical vapor co-deposition technique was proposed and successfully used to create a solar cell structure with a thin layer of hybrid perovskite as an energy-collecting material. A comprehensive analysis of methylammonium lead iodide behavior in a wide temperature range from 10 K to 320 K was carried out to implement this project. The initial phase included assessing the degradation of the perovskite material layer after cooling to the temperature of liquid helium and then re-heating it to room temperature. Then, using spectroscopic techniques, the characteristics of the layers' optical and electrical properties were determined. The obtained results allowed the design of the complete structure of a thin-film perovskite cell, which was made using only the vacuum sublimation process. Simulations using the SCAPS-1D program and experimental results showed high agreement and allowed for obtaining an efficiency of approximately 18.5 % in the interested temperature range. Perovskite solar cell stability tests over six months confirmed the positive impact of the proposed technique for depositing the complete cell structure on its temporal stability. The research results are optimistic for the applications of perovskite cells in space.

Hybrid organic-inorganic perovskites such as MAPbI₃ hold great promise for photovoltaic applications with power conversion efficiencies already exceeding 26 %. Despite the unprecedented advantages of these materials in photovoltaics and optoelectronics they exhibit a range of complex phenomena under light illumination that remain poorly understood. Here we use a combination of photoluminescence (PL) spectroscopy, cathodoluminescence imaging and theoretical calculations to correlate PL fluctuations in MAPbI₃ thin films with changes in the spatial distribution and concentration of native defects. We demonstrate that short-term illumination results in a more homogeneous distribution of emitting and quenching sites, whereas prolonged illumination causes PL quenching. Our findings support the conclusion that the photo-induced transformation of MAPbI₃ can be explained within a bistable amphoteric native defect model, wherein a neutral native defect can undergo a transition between a donor-like and acceptor-like configuration.

Viologens are considered among the most promising electrochromic materials for utilization in electrochromic devices (ECDs). In this regard, poly(butyl viologen) (PBV) has gained interest due to its stability, conductivity, and ease of synthesis, thus making it suitable for electrochromic applications. Regrettably, the poor adhesion of PBV thin film with substrates/electrodes deters the redox properties and long-term stability of PBV-based ECDs. To address this issue, herein, two types of surface-modified indium tin oxide (ITO) electrodes, grafted with 4-cyanophenol (P–CN-ITO) and benzyl phosphonic acid (BPO₃-ITO), are introduced for the deployment in PBV-based ECDs. The optical contrast (ΔT, %) for substrate-modified P–CN and BPO₃-based ECD was measured to be ∼57.0 and ∼59.5, respectively, which was remarkably higher (an improvement of ∼66 %) than that of ECD with bare ITO (∼34.3). Meanwhile, the coloration times (τ_c) of the P–CN, BPO_3, and bare ITO-based ECD were registered to be ∼1.7, ∼2.0, and ∼4.1 s, respectively, thus revealing the superiority of utilized functional groups over the unmodified substrate. The P–CN and BPO₃-based ECD retained ∼70.2 % and ∼55.5 % of initial ΔT, respectively, after continuous switching of 10,000 cycles, thus showing high endurance and reversibility. The XPS results indicated the strong covalent bond formation between the utilized functional groups (P–CN and BPO₃) and ITO, which delivered improved electrochemical, optical, and stability behavior when deployed in ECDs. Our study suggests that P–CN and BPO₃-based substrates can be promising for deployment as terminal electrodes in viologen-based ECDs for improved overall performance.

Multi-junction solar cells are the best technology to achieve high-efficiency photovoltaics. Yet, their thermal management is crucial to ensure high performance and reliability, particularly in concentrating photovoltaic systems. Recent studies have proposed radiative cooling as an innovative, passive, cost-effective, and scalable technique to cool down solar cells. In this study, we analyze its impact on multi-junction solar cells under different illumination conditions by means of a detailed-balance model. First, we demonstrate that radiative cooling can provide greater efficiency gain in multi-junction devices than in single-junction ones despite the fact that the former heat up less than the latter. In fact, in multi-junction cells, the lower heating is more than compensated for by the stronger efficiency degradation with increasing temperature, due to their wider radiative recombination spectrum. Then, we explore two possible strategies to effectively use radiative cooling in low-concentration photovoltaic systems, such as building integrated concentrating photovoltaics. The first one is to combine the radiative cooler with a nonradiative cooling system, which then has relaxed performance requirements. The second one is to increase the radiative cooler area relative to that of the solar cell. Both approaches can provide significant performance benefits, whose magnitude depends on the selected design and application. For an optimal triple-junction cell under 10-sun concentration, we find that a radiative cooler having 5$\times$ the area of the solar cell reduces by 90% the nonradiative cooling power required to maintain the cell temperature at 60 ${}^o$C and achieves +2% absolute efficiency gain over 1-sun operation.

Counter electrode (CE) is a key part of enhancing power conversion efficiency (PCE) and strengthening cyclic stability in quantum dot sensitized solar cells (QDSSCs). Consequently, searching for alternative and high-quality CE materials has far-reaching consequences for extending the lifetime, increasing utilization and even further achieving commercialization of QDSSCs. Herein, we put forward an idea that the Co₃S₄ hollow nanocages were coated with CuCo–B alloy-nanosheets, and efficient Co₃S₄@CuCo–B composite CE was prepared by in-situ reduction method, and applied to QDSSCs. Because of its three-dimensional hollow structure, the Co₃S₄@CuCo–B composite has a higher specific surface area, encourages electrolyte diffusion, and enhances QDSSC stability. Alternatively, the work function analysis shows that Co₃S₄ modified by CuCo–B enhances the driving force of interfacial electric field and promotes electron transfer. The photovoltaic performance of QDSSC assembled with Co₃S₄@CuCo–B composite CE has demonstrated competitive ability via implementing a PCE up to 8.27 %, J_sc = 26.45 mA cm⁻², V_oc = 0.683 V and FF = 0.46. Among them, the PCE of Co₃S₄@CuCo–B composite CE respectively has ∼14.4 % and 29.6 % enhancements in comparison with pure CuCo–B and Co₃S₄ CEs. And Co₃S₄@CuCo–B composite CE displays stable current density after 200 cycle tests, demonstrating excellent cyclic stability. This work suggests that Co₃S₄@CuCo–B composite lays the theoretical foundation for becoming a high-performance CE.

This paper focuses on the design and simulation of 2D Ruddlesden-Popper halide perovskite (RPHP) solar cells, emphasizing their optimization for indoor LED illumination conditions. The design process begins with the validation of physical models within the SCAPS device simulator, accomplished through careful calibration against experimental (MAMP)MA_n−1Pb_nI_3n+1 RPHP cell data. Subsequently, different values of <n> (with n = 1, 2, 3, and 4) are explored to study the impact of different band gap energies, aiming to identify the most suitable option for optimal efficiency across diverse LED color temperatures. By addressing both material-specific considerations and device architecture optimization, this study aims to establish a comprehensive framework for designing RPHP solar cells tailored for white LED illumination. Additionally, the simulation reveals that optimizing the electron affinity of the Electron Transport Layer (ETL) significantly impacts device performance, with efficiencies exceeding 25 %. Furthermore, the study discusses emerging trends such as ETL-free structures, which aim to address interface defects and enhance device performance. In addition, we analyze the impact of bulk trap density and thickness of the 2-D perovskite absorber on efficiency limitations. With an absorber thickness set at 800 nm, a marginal decrease in PCE is observed, for the ETL-free solar cell, from around 34 % to 32 % as the trap density ranges from 10¹¹ to 10¹⁴ cm⁻³. In contrast, for the ETL-based structure with the same variations, PCE experiences a substantial decline, dropping from approximately 47 % to 37 %. While the ETL-free structure may exhibit a lower PCE compared to the ETL-based cell, its capacity to endure fluctuations in trap density offers a notable advantage.

These efforts underscore the potential of 2D RPHP photovoltaic cells for indoor applications, presenting a pathway towards efficient, stable, and cost-effective photovoltaic technology suited for diverse lighting environments.

Efficient monitoring of solar cell performance in high-volume production lines is crucial to ensure consistency and stability. However, this task faces challenges as many manufacturing processes introduce efficiency variations. This study proposes a method, based on lag sequential analysis, to monitor and evaluate these variations. The proposed method is based on the analysis of time-series electrical measurements (such as open-circuit voltage, short-circuit current, fill factor, and efficiency) to identify the degree of randomness, trace process-induced batch variations, and assess line stability. Real-time application of the method can flag anomalies. Furthermore, the suggested method can be extended to image analysis by extracting relevant features from time-series luminescence images, enabling the study of whether cell defects in manufacturing exhibit a random pattern or possess distinguishable characteristics. With its various possible applications, the proposed method has significant potential in enhancing solar cell production line monitoring systems, enabling early identification of production issues and process improvement by manufacturers.

The CZTSSe absorber layer prepared with DMSO exhibits extensive cavities at its bottom, and a prominent double-layer structure is frequently observed within the CZTSSe absorber synthesized using DMF, both of which have a detrimental impact on the device performance. In this paper, an alternate spin-coating process using DMSO and DMF solvent systems is proposed, which eliminates the double-layer structure of CZTSSe and reduces the number of cavities at the bottom of the absorber layer, thereby enhancing its overall quality. This method outperforms the traditional single-solution spin-coating technique by combining the advantages of two solvent systems, allowing for the preparation of an ideal CZTSSe film without disturbing the elemental ratio, ultimately resulting in a single-layer absorber composed of large grains. After three repetitions of an identical alternate spin-coating process, the average grain size of the absorber layer increased from 0.83 to 1.21 μm. This innovative process leads to a reduction in carrier recombination and an improvement in the short-circuit current density, ultimately raising the photoelectric conversion efficiency from 7.40% to 8.88%.

The utilization of Latent Heat Thermal Energy Storage (LHTES) has gained significant attention to address the disparity between energy supply and demand. One of the key advantages lies in the use of phase change materials (PCM). The purpose of this research is to overcome this obstacle by focusing on enhancing the thermal efficiency of an advanced thermal energy storage system specifically designed for solar domestic and industrial application. to overcome this obstacle by focusing on enhancing the thermal efficiency of an advanced thermal energy storage system specifically designed for solar domestic and industrial application. Through computational and experimental studies, a novel and small LHTES system with parallel U-shaped heat exchanger (USHX) has been created and investigated. To improve performance, two approaches are employed: optimizing thermal efficiency by dispersing nano-sized graphite powders into the paraffin material, and/or incorporating metal foams. The PCM is RT35HC, and the hot/cold heat transfer fluid is H₂O, which travels via the U-shaped tube. The model incorporates the enthalpy-porosity technique to account for phase change phenomena. After comparing the numerical outcomes with the experiments herein run, data are shown in terms of liquid fraction, temperature evolution, stored energy, and a dimensionless parameter that characterizes the phase change process. The findings suggest that the proposed methods for enhancing heat transfer can enhance the thermal efficiency of systems. The outcomes illustrate that by addition of all methods, reduces the melting time by 13.39 %, 60.77 %, and 71.93 %, when compared to system with pure PCM.

Chloride salts, as high-temperature phase change materials (PCMs), have advantages in terms of high application temperature and high latent heat, but the intrinsic disadvantages such as high corrosiveness and easy leakage have seriously limited their development. Employing the NaCl–KCl binary salt as PCM, a double-shell cladding strategy with an inner layer of expanded graphite and an outer layer of ceramic was proposed, thereby, the chloride phase change macrocapsule with good thermal storage performance was successfully prepared. The double-shell capsules exhibited better leakage resistance and cycling stability. On this basis, the preparation process of double-shell eutectic salt macrocapsules was simplified by using an in-situ melting method, employing the mixed NaCl and KCl as raw materials directly that were transferred to eutectic binary salt inside the capsules during sintering. It is also proposed to improve the heat storage density of the capsules by increasing the capsule size and isostatically pressing the capsule. The NaK-20-200MPa sample indicated the largest heat storage density in the temperature range from 600 °C to 700 °C, with a mass heat storage density of 190.38 J/g, which was 2.85 % higher than that of the NaK-20-0MPa capsules and 36.99 % higher than that of the NaK-5-0MPa capsules. Additionally, the volume heat storage density of the NaK-20-200MPa capsules was 339.19 J/cm³, which was 14.69 % higher than that of the NaK-20-0MPa capsules and 21.52 % higher than that of the NaK-5-0MPa capsules. The good thermal performance and low cost of chloride PCM could ensure the encapsulated salt for use in high-temperature heat storage.